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In this episode of SpaceTime, we unveil a stunning new ultraviolet map of the Milky Way galaxy, thanks to NASA's New Horizons spacecraft. This groundbreaking observation, published in the Astronomical Journal, provides astronomers with unprecedented insights into the galactic environment surrounding our solar system. We discuss how these findings challenge existing theories about interstellar hydrogen emissions and reveal the complex structures of hot interstellar gas bubbles.
Exploring Mars with Perseverance
Next, we follow NASA's Perseverance Rover as it investigates the intriguing rock formations at the Jezero crater rim. Discover how the rover is analyzing the contrasting layers of rock, searching for clues about Mars's geological history and the processes that shaped its surface.
Psyche Spacecraft Troubles
Finally, we address the ongoing investigation into a significant issue with the electric propulsion system of NASA's Psyche spacecraft. Launched in 2023, this mission aims to explore the metallic asteroid 16 Psyche. We delve into the challenges faced by mission managers and discuss potential solutions to ensure the spacecraft continues on its path to unravel the mysteries of planetary cores.
www.spacetimewithstuartgary.com (https://www.spacetimewithstuartgary.com/)
✍️ Episode References
Astronomical Journal
https://iopscience.iop.org/journal/0004-637X (https://iopscience.iop.org/journal/0004-637X)
NASA Perseverance Rover
https://mars.nasa.gov/mars2020/ (https://mars.nasa.gov/mars2020/)
NASA Psyche Mission
https://www.nasa.gov/psyche (https://www.nasa.gov/psyche)
Become a supporter of this podcast: https://www.spreaker.com/podcast/spacetime-space-astronomy--2458531/support (https://www.spreaker.com/podcast/spacetime-space-astronomy--2458531/support?utm_source=rss&utm_medium=rss&utm_campaign=rss) .
00:00 This is Space Time Series 28, episode 56 for broadcast on 9 May 2025
00:45 NASA's New Horizons spacecraft reveals a new ultraviolet map of the Milky Way
12:30 Mars Perseverance Rover continues its exploration of Jezero crater
18:15 NASA investigates issues with the Psyche spacecraft's electric propulsion system
22:00 Skywatch: May night skies and celestial events
Episode link: https://play.headliner.app/episode/27035891?utm_source=youtube
00:00:00 --> 00:00:03 This is Spacetime Series 28, episode 56
00:00:03 --> 00:00:06 for broadcast on the 9th of May,
00:00:06 --> 00:00:09 2025. Coming up on Spaceime, a stunning
00:00:09 --> 00:00:12 new map of the nearby Milky Way galaxy,
00:00:12 --> 00:00:15 searching for the dark in Martian light,
00:00:15 --> 00:00:17 and NASA investigating problems with the
00:00:17 --> 00:00:20 Psyche spacecraft's thruster system. All
00:00:20 --> 00:00:24 that and more coming up on Spaceime.
00:00:24 --> 00:00:28 Welcome to Spaceime with Stuart Garry.
00:00:28 --> 00:00:35 [Music]
00:00:43 --> 00:00:45 NASA's New Horizon spacecraft has
00:00:45 --> 00:00:47 provided astronomers with an important
00:00:47 --> 00:00:50 new ultraviolet map of our galaxy, the
00:00:50 --> 00:00:52 Milky Way. The spectacular new
00:00:52 --> 00:00:53 observations reported in the
00:00:53 --> 00:00:56 astronomical journal use a specific
00:00:56 --> 00:00:58 ultraviolet wavelength, shedding new
00:00:58 --> 00:01:00 light on structures and processes in the
00:01:00 --> 00:01:02 galactic region surrounding our solar
00:01:02 --> 00:01:05 system. In fact, these new landmark
00:01:05 --> 00:01:07 observations are providing astronomers
00:01:07 --> 00:01:09 with their first clear view of the sky
00:01:09 --> 00:01:10 surrounding the solar system at these
00:01:10 --> 00:01:12 wavelengths, and they're revealing both
00:01:12 --> 00:01:14 new characteristics of that sky and
00:01:14 --> 00:01:17 refuting old ideas. The study's lead
00:01:18 --> 00:01:20 author Randy Gladston from the Southwest
00:01:20 --> 00:01:22 Research Institute says the new findings
00:01:22 --> 00:01:24 are showing hot interstellar gas bubbles
00:01:24 --> 00:01:26 like the one our solar systems embedded
00:01:26 --> 00:01:28 within may actually be regions of
00:01:28 --> 00:01:29 enhanced hydrogen gas emissions at
00:01:29 --> 00:01:33 wavelengths known as lyman alpha. Lyman
00:01:33 --> 00:01:35 alpha is a specific wavelength of
00:01:35 --> 00:01:37 ultraviolet light emitted and scattered
00:01:37 --> 00:01:40 by hydrogen atoms. It's especially
00:01:40 --> 00:01:42 useful to astronomers studying distant
00:01:42 --> 00:01:44 stars, galaxies, and the interstellar
00:01:44 --> 00:01:46 medium as it can help detect the
00:01:46 --> 00:01:47 composition, temperature, and movement
00:01:47 --> 00:01:49 of these distant objects. During its
00:01:49 --> 00:01:52 initial journey to Pluto, New Horizons
00:01:52 --> 00:01:54 collected baseline data about lime and
00:01:54 --> 00:01:56 alpha emissions using its Alice
00:01:56 --> 00:01:58 ultraviolet spectrograph. Spectrograph
00:01:58 --> 00:02:00 split light into various wavelengths of
00:02:00 --> 00:02:03 colors, and Alice specializes in the far
00:02:03 --> 00:02:06 ultraviolet wavelength band. After the
00:02:06 --> 00:02:08 spacecraft's primary flyby of the dwarf
00:02:08 --> 00:02:10 planet Pluto and its binary partner
00:02:10 --> 00:02:12 Sharon, scientists used Alice to make
00:02:12 --> 00:02:14 broader and more frequent surveys of
00:02:14 --> 00:02:16 lime and alpha emissions as new horizons
00:02:16 --> 00:02:18 traveled further from the sun. These
00:02:18 --> 00:02:20 surveys included an extensive set of
00:02:20 --> 00:02:24 scans mapping roughly 83% of the sky. To
00:02:24 --> 00:02:26 isolate emissions from the galaxy,
00:02:26 --> 00:02:27 astronomers modeled scattered solar
00:02:28 --> 00:02:29 limema alpha emissions and then
00:02:29 --> 00:02:31 subtracted them from the specttograph's
00:02:31 --> 00:02:34 data. The results indicate a roughly
00:02:34 --> 00:02:36 uniform background lime and alpha sky
00:02:36 --> 00:02:38 brightness 10 times stronger than what
00:02:38 --> 00:02:40 was expected from previous estimates.
00:02:40 --> 00:02:42 Gladston says the results point to the
00:02:42 --> 00:02:44 emission and scattering of lime and
00:02:44 --> 00:02:46 alpha photons by hydrogen atoms in the
00:02:46 --> 00:02:48 shell of a hot bubble known as surround
00:02:48 --> 00:02:51 our solar system nearby stars. That
00:02:51 --> 00:02:53 bubble was formed by nearby supernova
00:02:53 --> 00:02:55 events millions of years ago. The study
00:02:55 --> 00:02:57 also found no evidence that a hydrogen
00:02:57 --> 00:02:59 wall thought to surround the sun's
00:02:59 --> 00:03:01 heliosphere substantially contributes to
00:03:01 --> 00:03:03 the observed lime and alpha signal.
00:03:03 --> 00:03:05 Astronomers had theorized that a wall of
00:03:05 --> 00:03:07 interstellar hydrogen atoms would
00:03:07 --> 00:03:09 accumulate as they encountered the edge
00:03:09 --> 00:03:11 of the heliosphere. The vast region of
00:03:11 --> 00:03:13 space encapsulating our solar system
00:03:13 --> 00:03:16 dominated by the solar wind. However,
00:03:16 --> 00:03:18 the new horizon's data saw nothing to
00:03:18 --> 00:03:20 indicate the wall is an important source
00:03:20 --> 00:03:23 of lime and alpha emissions. This is
00:03:23 --> 00:03:26 spaceime still to come. Searching for
00:03:26 --> 00:03:29 the dark in the Martian light and NASA
00:03:29 --> 00:03:30 mission managers are investigating a
00:03:30 --> 00:03:32 major problem with the electric
00:03:32 --> 00:03:34 propulsion system aboard its Psyche
00:03:34 --> 00:03:36 spacecraft. All that and more still to
00:03:36 --> 00:03:38 come on
00:03:38 --> 00:03:40 [Music]
00:03:40 --> 00:03:42 Spaceime. This episode of Spacetime is
00:03:42 --> 00:03:45 brought to you by NordVPN, our official
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00:05:01 --> 00:05:10 [Music]
00:05:10 --> 00:05:12 NASA's Mars Perseverance rover has been
00:05:12 --> 00:05:14 busy over the past week continuing its
00:05:14 --> 00:05:15 exploration of the lower witch Hazel
00:05:15 --> 00:05:17 Hill outcrop exposed on the edge of the
00:05:17 --> 00:05:20 Jezro crater rim. The formations
00:05:20 --> 00:05:22 composed of alternating light and dark
00:05:22 --> 00:05:25 layers of rock and mission managers have
00:05:25 --> 00:05:26 been busy trying to understand the
00:05:26 --> 00:05:29 makeup and relationship of these layers.
00:05:29 --> 00:05:31 A few weeks ago, they sampled one of the
00:05:31 --> 00:05:33 light tone layers at a place they've
00:05:33 --> 00:05:35 named Maine River. They discovered it
00:05:35 --> 00:05:36 was made up of very small clasts or
00:05:36 --> 00:05:39 fragments of rocks and minerals. Since
00:05:39 --> 00:05:41 then, scientists have learned that the
00:05:41 --> 00:05:43 darker layers tend to be composed of
00:05:43 --> 00:05:45 larger classs compared to the lighter
00:05:45 --> 00:05:47 layers, and they've been searching for a
00:05:47 --> 00:05:49 place to sample this coarser grain rock
00:05:49 --> 00:05:51 type. Sometimes these coarser grain
00:05:51 --> 00:05:53 rocks also contain sphererals which are
00:05:53 --> 00:05:55 of great interest to scientists because
00:05:55 --> 00:05:56 they provide clues about the very
00:05:56 --> 00:05:58 processes that form the layered rock
00:05:58 --> 00:06:00 formations in the first place.
00:06:00 --> 00:06:02 Perseverance first looked at a dark
00:06:02 --> 00:06:05 layer at punchon rock using its abrasion
00:06:05 --> 00:06:07 tool. They then examined another dark
00:06:07 --> 00:06:09 layer at a formation known as wreck
00:06:09 --> 00:06:11 apple but couldn't find a suitable space
00:06:11 --> 00:06:14 to araid. So while scientists searched
00:06:14 --> 00:06:16 for other locations to study the coarse
00:06:16 --> 00:06:18 grain units and sphererals, Perseverance
00:06:18 --> 00:06:20 drove further south to a place known as
00:06:20 --> 00:06:23 Port Anson. Port Anson's intriguing
00:06:23 --> 00:06:25 because from orbit it showed a clear
00:06:25 --> 00:06:27 contact between the lighter layers of
00:06:27 --> 00:06:29 witch hazel hill and a distinct unit
00:06:29 --> 00:06:31 below it. And although the rocks below
00:06:31 --> 00:06:33 the poansen contact point do show
00:06:34 --> 00:06:35 interesting compositional differences
00:06:35 --> 00:06:37 with those of witch hazel hill, they
00:06:37 --> 00:06:38 weren't the coarse grain rocks
00:06:38 --> 00:06:40 scientists were looking for. Still, they
00:06:40 --> 00:06:42 did perform an abrasion test there at a
00:06:42 --> 00:06:44 location they've named Strong Island
00:06:44 --> 00:06:46 before driving back up north for what
00:06:46 --> 00:06:48 hopefully will be another attempt at
00:06:48 --> 00:06:51 investigating the coarser grain rocks.
00:06:51 --> 00:06:53 Needless to say, we'll keep you
00:06:53 --> 00:06:56 informed. This is Spaceime. Still to
00:06:56 --> 00:06:58 come, NASA mission managers
00:06:58 --> 00:07:00 investigating a serious problem with the
00:07:00 --> 00:07:01 electric propulsion system aboard its
00:07:01 --> 00:07:04 Psyche spacecraft. And we explore the
00:07:04 --> 00:07:06 constellation Scorpius, the spectacular
00:07:06 --> 00:07:09 M6 and M7 open star clusters, and the
00:07:09 --> 00:07:12 ETAs meteor shower produced by Hal's
00:07:12 --> 00:07:15 Comet in the May edition of Skywatch.
00:07:15 --> 00:07:23 [Music]
00:07:30 --> 00:07:32 NASA mission managers are investigating
00:07:32 --> 00:07:33 a problem with the electric propulsion
00:07:33 --> 00:07:36 system aboard the Saki spacecraft.
00:07:36 --> 00:07:37 Launched on a Falcon Heavy rocket back
00:07:38 --> 00:07:42 in October 2023, the 2,68 kg probe is on
00:07:42 --> 00:07:44 a mission to explore the metallic main
00:07:44 --> 00:07:47 belt asteroid 16 Psyche in order to
00:07:47 --> 00:07:49 learn more about the origins of
00:07:49 --> 00:07:52 planetary cores. 16 Sakis, the heaviest
00:07:52 --> 00:07:55 known Mtype asteroid, and it may be the
00:07:55 --> 00:07:57 exposed iron core of a protolanet, the
00:07:57 --> 00:07:59 remnant of a violent collision with
00:07:59 --> 00:08:01 another object that stripped this body
00:08:01 --> 00:08:04 off its metal and crust. The spacecraft
00:08:04 --> 00:08:06 will eventually spend 817 Earth days
00:08:06 --> 00:08:09 orbiting the strange 226 km wide
00:08:09 --> 00:08:11 metallic world. But it's got to get
00:08:11 --> 00:08:13 there first. Mission managers with
00:08:14 --> 00:08:15 NASA's Jet Propulsion Laboratory in
00:08:15 --> 00:08:17 Pasin, California, say the spacecraft's
00:08:17 --> 00:08:19 electric thrusters shut down on April
00:08:19 --> 00:08:21 the 1st when pressure fell in the line
00:08:22 --> 00:08:24 that feeds Xeon propellant to the Hall
00:08:24 --> 00:08:26 effect thrusters. The pressure dropped
00:08:26 --> 00:08:29 from 248 kilopascals down to 179,
00:08:29 --> 00:08:31 causing the thrusters to stop working.
00:08:31 --> 00:08:33 The probe turned on its hall effect
00:08:33 --> 00:08:36 thrusters in May 2024, which combined
00:08:36 --> 00:08:38 with a gravity assist Mars flyby
00:08:38 --> 00:08:40 scheduled for May next year will allow
00:08:40 --> 00:08:43 the probe to arrive at Psyche in August
00:08:43 --> 00:08:45 2029. Now, right now, there's not too
00:08:45 --> 00:08:47 much to worry about. Psyche can continue
00:08:47 --> 00:08:49 to coast until the middle of June before
00:08:49 --> 00:08:51 there's a significant effect on its
00:08:51 --> 00:08:53 trajectory. Right now, potential
00:08:53 --> 00:08:55 solutions include switching to a backup
00:08:55 --> 00:08:57 propellant line. It's the first major
00:08:57 --> 00:08:59 problem with the spacecraft which had
00:08:59 --> 00:09:00 been working normally since its long
00:09:00 --> 00:09:03 delayed launch. See, the project had
00:09:03 --> 00:09:04 suffered a series of development
00:09:04 --> 00:09:07 problems during its construction phase.
00:09:07 --> 00:09:09 These included the co pandemic and
00:09:09 --> 00:09:11 software testing delays which pushed
00:09:11 --> 00:09:13 back the launch date from the originally
00:09:13 --> 00:09:17 slated August 2022 by more than a year.
00:09:17 --> 00:09:23 This is spaceime
00:09:23 --> 00:09:35 [Music]
00:09:35 --> 00:09:36 And time now to turn our eyes to the
00:09:36 --> 00:09:38 skies and check out the celestial sphere
00:09:38 --> 00:09:42 for the month of May on Skywatch. May is
00:09:42 --> 00:09:43 the fifth month of the year in both the
00:09:43 --> 00:09:46 Julian and Gagorian calendars. The month
00:09:46 --> 00:09:49 was named for the Greek goddess Maya who
00:09:49 --> 00:09:51 was identified with the Roman era
00:09:51 --> 00:09:53 goddess of fertility Bonadia whose
00:09:53 --> 00:09:55 festival was held in May. But I guess
00:09:55 --> 00:09:57 more importantly for many of our
00:09:57 --> 00:09:59 listeners, May typically marks the start
00:09:59 --> 00:10:01 of summer vacation season in the United
00:10:01 --> 00:10:04 States and Canada. Let's start our tour
00:10:04 --> 00:10:06 of the night skies by looking east where
00:10:06 --> 00:10:08 you'll see the constellation Scorpius,
00:10:08 --> 00:10:11 the Scorpion. In Greek mythology, the
00:10:11 --> 00:10:13 constellation was named after Scorpius,
00:10:13 --> 00:10:14 who was sent to Earth by the goddess
00:10:14 --> 00:10:17 Gaia, in order to slay Orion, the
00:10:17 --> 00:10:18 Hunter, after he boasted that he could
00:10:18 --> 00:10:21 kill all the animals on Earth. Scorpius
00:10:21 --> 00:10:24 stung Orion in the shoulder. But Orion's
00:10:24 --> 00:10:27 life was spared by Ofious, the healer,
00:10:27 --> 00:10:29 and it was placed in the heavens along
00:10:29 --> 00:10:31 with Scorpius, who continues to pursue
00:10:31 --> 00:10:34 him for eternity. Orion the hunter has
00:10:34 --> 00:10:36 become the hunted forever with Scorpius
00:10:36 --> 00:10:39 rising in the east this time of year to
00:10:39 --> 00:10:41 triumphantly chase and defeat Orion who
00:10:41 --> 00:10:44 sets in the west. Meanwhile, Ofucius the
00:10:44 --> 00:10:46 healer rises in the east following
00:10:46 --> 00:10:48 behind Scorpius to chase and crush him
00:10:48 --> 00:10:50 into the earth as the scorpion sets in
00:10:50 --> 00:10:53 the west. And so this ancient story
00:10:53 --> 00:10:55 continues to play out in the heavens
00:10:55 --> 00:10:58 year after year. Interestingly, parts of
00:10:58 --> 00:11:01 the story predate the Greeks with Orion
00:11:01 --> 00:11:03 known in ancient Egypt as Osiris, the
00:11:03 --> 00:11:05 god of the underworld and of
00:11:05 --> 00:11:07 regeneration. The brightest star in
00:11:08 --> 00:11:10 Scorpius is Alpha Scorpio or Antares,
00:11:10 --> 00:11:13 the scorpion's heart. In ancient Greek,
00:11:13 --> 00:11:15 the name Antares means the equal arrival
00:11:15 --> 00:11:18 of Mars, the god of war. That's because
00:11:18 --> 00:11:20 its golden orange appearance is similar
00:11:20 --> 00:11:22 to that of the red planet, and it passes
00:11:22 --> 00:11:26 very close to Mars every 780 years.
00:11:26 --> 00:11:28 easily seen with the unaded eye and
00:11:28 --> 00:11:32 Tares is some 550 lighty years away but
00:11:32 --> 00:11:34 it looks so bright because it's around
00:11:34 --> 00:11:37 57 times as luminous as the sun and
00:11:37 --> 00:11:40 is one of the largest known stars in the
00:11:40 --> 00:11:44 universe. Ant is a red super giant about
00:11:44 --> 00:11:47 18 times the mass and 883 times the
00:11:47 --> 00:11:49 diameter of the sun. Were it placed
00:11:49 --> 00:11:51 where the sun is in our solar system, it
00:11:52 --> 00:11:53 would engulf all the terrestrial
00:11:53 --> 00:11:55 planets, Mercury, Venus, Earth, and
00:11:55 --> 00:11:57 Mars. And its visible surface would
00:11:57 --> 00:12:00 extend almost as far out as Jupiter. A
00:12:00 --> 00:12:02 lightyear is about 10 trillion
00:12:02 --> 00:12:04 kilometers. The distance a photon can
00:12:04 --> 00:12:08 travel in a year at 300 km/s, the
00:12:08 --> 00:12:10 speed of light in a vacuum, and the
00:12:10 --> 00:12:12 ultimate speed limit of the universe.
00:12:12 --> 00:12:15 Astronomers believe Antaris began life
00:12:15 --> 00:12:17 around 12 million years ago as a
00:12:17 --> 00:12:19 spectrotype O or B blue star.
00:12:19 --> 00:12:22 Astronomers describe stars in terms of
00:12:22 --> 00:12:24 spectral types, a classification system
00:12:24 --> 00:12:25 based on temperature and
00:12:25 --> 00:12:27 characteristics. The hottest, most
00:12:27 --> 00:12:29 massive, and most luminous stars are
00:12:29 --> 00:12:32 known as spectrotype O blue stars.
00:12:32 --> 00:12:34 They're followed by spectrotype B blue
00:12:34 --> 00:12:37 white stars. Then spectrotype A white
00:12:37 --> 00:12:39 stars, spectrotype F whitish yellow
00:12:39 --> 00:12:42 stars, spectrotype G yellow stars.
00:12:42 --> 00:12:44 That's where our sun fits in. Then
00:12:44 --> 00:12:46 there's spectrotype K orange stars. And
00:12:46 --> 00:12:48 the coolest and least massive stars are
00:12:48 --> 00:12:52 known as spectrotype M red stars. Each
00:12:52 --> 00:12:54 spectral classification system can also
00:12:54 --> 00:12:56 be subdivided using a numeric digit to
00:12:56 --> 00:12:58 represent temperature with zero being
00:12:58 --> 00:13:01 the hottest and nine the coolest. And
00:13:01 --> 00:13:02 then you add a Roman numeral to
00:13:02 --> 00:13:05 represent luminosity. So put it all
00:13:05 --> 00:13:07 together and you can describe our sun as
00:13:07 --> 00:13:12 being a G2V or G25 yellow dwarf star,
00:13:12 --> 00:13:14 one of millions spread across our
00:13:14 --> 00:13:17 galaxy. Also included in the stellar
00:13:17 --> 00:13:19 classification system are special types
00:13:19 --> 00:13:21 LT and Y which are assigned to failed
00:13:21 --> 00:13:24 stars known as brown dwarves. Some of
00:13:24 --> 00:13:25 which were actually born as spectrotype
00:13:26 --> 00:13:28 M red stars but became brown dwarves
00:13:28 --> 00:13:31 after losing some of their mass. Brown
00:13:31 --> 00:13:33 dwarves fit into a unique category
00:13:33 --> 00:13:34 between the largest planets, which are
00:13:34 --> 00:13:36 about 13 times the mass of Jupiter, and
00:13:36 --> 00:13:38 the smallest spectrotype M red dwarf
00:13:38 --> 00:13:41 stars, which are about 75 to 80 times
00:13:41 --> 00:13:44 the mass of Jupiter, or 0.08 solar
00:13:45 --> 00:13:47 masses. Like the similarsized red giant
00:13:47 --> 00:13:50 Betalers in the constellation Orion,
00:13:50 --> 00:13:52 Antares will almost certainly end its
00:13:52 --> 00:13:54 life as a spectacular type 2 or core
00:13:54 --> 00:13:57 collapse supernova, probably sometime
00:13:57 --> 00:13:59 within the next 100 years or so.
00:13:59 --> 00:14:01 When it does explode, it'll appear as
00:14:01 --> 00:14:03 bright as the full moon for several
00:14:03 --> 00:14:05 months on end and will be clearly
00:14:05 --> 00:14:07 visible during daylight hours here on
00:14:07 --> 00:14:10 Earth. Antares has a companion star,
00:14:10 --> 00:14:15 Antares B, located between 224 and 529
00:14:15 --> 00:14:16 astronomical units away from the
00:14:16 --> 00:14:19 primary. An astronomical unit is the
00:14:19 --> 00:14:21 average distance between the Earth and
00:14:21 --> 00:14:23 the Sun, which is about 150 million
00:14:23 --> 00:14:27 kilome or 8.3 light minutes. Spectral
00:14:27 --> 00:14:29 analysis of Antares B indicates it's
00:14:29 --> 00:14:31 pulling a lot of material off its
00:14:31 --> 00:14:33 bloated red super giant
00:14:33 --> 00:14:36 companion. Located near Antares is the
00:14:36 --> 00:14:40 M4 globular cluster. Globular clusters
00:14:40 --> 00:14:42 are tight balls densely packed with
00:14:42 --> 00:14:44 thousands to millions of stars which
00:14:44 --> 00:14:46 were either all originally formed at the
00:14:46 --> 00:14:47 same time from the collapse of the same
00:14:48 --> 00:14:49 molecular gas and dust cloud or
00:14:50 --> 00:14:52 alternatively their galactic centers.
00:14:52 --> 00:14:54 the remains of ancient galaxies that
00:14:54 --> 00:14:55 have been merged into the Milky Way
00:14:55 --> 00:14:59 galaxy over billions of years. M4 is
00:14:59 --> 00:15:01 composed of a million or so stars
00:15:01 --> 00:15:03 originally born some 12 billion years
00:15:03 --> 00:15:06 ago. The M4 globular cluster is located
00:15:06 --> 00:15:09 some 7 light years away, making it
00:15:09 --> 00:15:11 one of the nearest globular clusters to
00:15:11 --> 00:15:13 Earth. Easily seen through a pair of
00:15:13 --> 00:15:16 small binoculars, it covers an area of
00:15:16 --> 00:15:18 the sky as seen from Earth as big as the
00:15:18 --> 00:15:21 full moon. Astronomers estimate there
00:15:21 --> 00:15:23 are some 150 or so globular clusters
00:15:23 --> 00:15:26 orbiting in the halo of the Milky
00:15:26 --> 00:15:28 Way. Located near the tail of the
00:15:28 --> 00:15:31 scorpion are two open star clusters
00:15:31 --> 00:15:34 known as M6 and M7. Open star clusters
00:15:34 --> 00:15:36 are loosely bound groups of a few
00:15:36 --> 00:15:38 thousand stars which all originally
00:15:38 --> 00:15:40 formed from the same molecular gas and
00:15:40 --> 00:15:42 dust cloud at the same time but are not
00:15:42 --> 00:15:45 as densely bound as globular clusters.
00:15:45 --> 00:15:47 Open clusters generally survive for a
00:15:47 --> 00:15:49 few hundred million years with the most
00:15:49 --> 00:15:50 massive ones surviving for maybe a few
00:15:50 --> 00:15:53 billion years. Now, in contrast, the far
00:15:53 --> 00:15:56 more massive globular clusters exert far
00:15:56 --> 00:15:57 stronger gravitational attraction on
00:15:58 --> 00:15:59 their members, which is why they can
00:15:59 --> 00:16:02 survive so much longer. M6, which is
00:16:02 --> 00:16:04 also known as the butterfly cluster, is
00:16:04 --> 00:16:06 some 12 light years across and located
00:16:06 --> 00:16:09 about 1 lighty years away. It
00:16:09 --> 00:16:11 contains around 80 stars which are all
00:16:11 --> 00:16:13 less than 100 million years old which is
00:16:13 --> 00:16:17 quite young in cosmic terms. The M7 or
00:16:17 --> 00:16:19 Tom cluster is named after the famous
00:16:19 --> 00:16:21 Greek astronomer and mathematician
00:16:21 --> 00:16:24 Claudius Tom. It's about 980 light years
00:16:24 --> 00:16:27 away and is far more dispersed than M6
00:16:27 --> 00:16:29 covering an area around 25 lighty years
00:16:29 --> 00:16:32 across. And at around 200 million years,
00:16:32 --> 00:16:35 it's about twice as old.
00:16:35 --> 00:16:39 By the way, the M in terms like M4, M6,
00:16:39 --> 00:16:42 and M7 are abbreviations for Messier in
00:16:42 --> 00:16:43 honor of the 18th century French
00:16:43 --> 00:16:45 astronomer Charles Messier, who
00:16:45 --> 00:16:47 developed an astronomical catalog of
00:16:47 --> 00:16:50 fuzzy, nebulous objects in the skies.
00:16:50 --> 00:16:53 See, Messier was a comet hunter, and he
00:16:53 --> 00:16:55 compiled a list of 103 fuzzy objects
00:16:56 --> 00:16:58 which weren't comets, and so from his
00:16:58 --> 00:17:00 perspective could be ignored. Later,
00:17:00 --> 00:17:02 other astronomers added additional
00:17:02 --> 00:17:04 celestial objects to the list, bringing
00:17:04 --> 00:17:06 the present catalog up to
00:17:06 --> 00:17:09 110. Our solar system, in fact, most of
00:17:09 --> 00:17:11 the stars we see when we look up in the
00:17:11 --> 00:17:13 night sky, are located in the Milky Way
00:17:13 --> 00:17:17 galaxy's Orion arm. The Orion arm, also
00:17:17 --> 00:17:19 known as the Orion spur or the Orion
00:17:19 --> 00:17:21 Signis arm, depending on which name you
00:17:21 --> 00:17:24 prefer, is some 3 lighty years wide
00:17:24 --> 00:17:27 and around 10 lighty years long. The
00:17:27 --> 00:17:30 Orion arm is named after the Orion
00:17:30 --> 00:17:31 constellation which is one of the most
00:17:32 --> 00:17:33 prominent constellations in the southern
00:17:33 --> 00:17:35 hemisphere summer and northern
00:17:35 --> 00:17:37 hemisphere winter. Some of the brightest
00:17:38 --> 00:17:40 and most famous celestial objects in the
00:17:40 --> 00:17:43 constellation include bettle riel the
00:17:43 --> 00:17:45 stars of the Orion belt and the Orion
00:17:45 --> 00:17:48 nebula all located within the Orion arm.
00:17:48 --> 00:17:50 The Orion arm is located between the
00:17:50 --> 00:17:53 Karina Sagittarius arm which is more
00:17:53 --> 00:17:54 towards the galactic center from our
00:17:54 --> 00:17:57 position and the Perseus arm which is
00:17:57 --> 00:17:58 more towards the outer edge of the
00:17:58 --> 00:18:00 galaxy from our point of view. The
00:18:00 --> 00:18:02 Perseus arm is one of the two major arms
00:18:02 --> 00:18:04 of the Milky Way. The other being the
00:18:04 --> 00:18:07 Scutum Centurus arm. Long thought of as
00:18:07 --> 00:18:10 a minor structure, a spur if you will
00:18:10 --> 00:18:12 between the two longer adjacent arms,
00:18:12 --> 00:18:15 Perseus and Karina Sagittarius. Evidence
00:18:15 --> 00:18:17 was presented in mid 2013 that the Orion
00:18:17 --> 00:18:19 arm might actually be a branch of the
00:18:19 --> 00:18:21 Perseus arm or possibly a completely
00:18:21 --> 00:18:24 independent arm segment itself. Within
00:18:24 --> 00:18:27 the Orion arm, our solar system, the
00:18:27 --> 00:18:28 sun, the Earth, and all the other
00:18:28 --> 00:18:30 planets we know are located close to the
00:18:30 --> 00:18:32 inner rim in what's known as the local
00:18:32 --> 00:18:35 bubble. About halfway along the Orion
00:18:35 --> 00:18:37 arm's length, approximately 26 light
00:18:37 --> 00:18:40 years from the galactic center. The
00:18:40 --> 00:18:42 local bubble is a cavity in the
00:18:42 --> 00:18:44 interstellar medium in the Orion arm
00:18:44 --> 00:18:45 containing among other things the local
00:18:45 --> 00:18:47 interstellar cloud which contains our
00:18:47 --> 00:18:50 solar system and the G-Cloud. It's at
00:18:50 --> 00:18:53 least 300 light years across and it has
00:18:53 --> 00:18:56 a neutral hydrogen density of just 0.05
00:18:56 --> 00:18:59 atoms per cm. That's just 1/10enth of
00:18:59 --> 00:19:01 the average for the interstellar medium
00:19:01 --> 00:19:03 across the Milky Way and about a sixth
00:19:04 --> 00:19:06 that of the local interstellar cloud.
00:19:06 --> 00:19:08 The hot diffused gas in the local bubble
00:19:08 --> 00:19:10 emits X-rays and is the result of a
00:19:10 --> 00:19:12 supernova that exploded sometime during
00:19:12 --> 00:19:15 the past 10 to 20 million years. It was
00:19:15 --> 00:19:17 once thought that the most likely
00:19:17 --> 00:19:18 candidate for the remains of this
00:19:18 --> 00:19:21 supernova was Jiminga, a pulsar in the
00:19:21 --> 00:19:24 constellation Gemini. However, later it
00:19:24 --> 00:19:26 was suggested that modable supernova in
00:19:26 --> 00:19:29 a subgroup B1 of the Plleades moving
00:19:29 --> 00:19:31 group was more likely responsible
00:19:31 --> 00:19:33 becoming a remnant super shell. Our
00:19:34 --> 00:19:35 solar system has been traveling through
00:19:35 --> 00:19:37 this region of space occupied by the
00:19:37 --> 00:19:39 local bubble for the last 5 to 10
00:19:39 --> 00:19:42 million years. Its current location is
00:19:42 --> 00:19:43 in what's known as the local
00:19:44 --> 00:19:46 interstellar cloud. A minor region of
00:19:46 --> 00:19:48 slightly denser material within the
00:19:48 --> 00:19:50 bubble. The cloud formed when the local
00:19:50 --> 00:19:52 bubble and another bubble called the
00:19:52 --> 00:19:55 loop one bubble met. Gas within the
00:19:55 --> 00:19:57 local interstellar cloud has a density
00:19:57 --> 00:20:01 of about 0.3 atoms per cm. From what we
00:20:01 --> 00:20:02 can tell, the local bubble isn't
00:20:02 --> 00:20:05 spherical, but seems to be narrower in
00:20:05 --> 00:20:07 the galactic plane, becoming somewhat
00:20:07 --> 00:20:09 egg- shaped or elliptical, and may even
00:20:09 --> 00:20:11 become wider above and below the
00:20:11 --> 00:20:13 galactic plane, becoming shaped more
00:20:13 --> 00:20:15 like an hourglass. And it's not alone.
00:20:15 --> 00:20:17 It's abuting other bubbles of lesser
00:20:18 --> 00:20:20 dense interstellar medium, including the
00:20:20 --> 00:20:22 loop one bubble. The loop one bubble was
00:20:22 --> 00:20:25 created by supernova and stellar winds
00:20:25 --> 00:20:27 in the Scorpio Centurus Association,
00:20:27 --> 00:20:29 some 500 light years from the sun. The
00:20:30 --> 00:20:32 loop one bubble also contains the star
00:20:32 --> 00:20:34 antures that we spoke about earlier.
00:20:34 --> 00:20:36 Astronomers have identified several well
00:20:36 --> 00:20:38 I guess you'd call them tunnels which
00:20:38 --> 00:20:40 connect the cavities of the local bubble
00:20:40 --> 00:20:42 with that of the loop one bubble.
00:20:42 --> 00:20:44 Collectively they've been referred to as
00:20:44 --> 00:20:46 the lupus tunnel. Other bubbles which
00:20:46 --> 00:20:48 are adjacent to our local bubble and
00:20:48 --> 00:20:50 known as the loop 2 bubble and the loop
00:20:50 --> 00:20:52 three bubble. Looks like astronomers
00:20:52 --> 00:20:54 still have a problem when it comes to
00:20:54 --> 00:20:56 thinking up cool names.
00:20:56 --> 00:20:58 Also visible this month is the ETA
00:20:58 --> 00:21:01 awards meteor shower which is generated
00:21:01 --> 00:21:03 as the Earth passes through the dust and
00:21:03 --> 00:21:05 debris trail left behind by Hal's comet.
00:21:06 --> 00:21:08 Comet P1's a well-known short period
00:21:08 --> 00:21:10 comet which visits the inner solar
00:21:10 --> 00:21:14 system every 75 to 76 years. The 15
00:21:14 --> 00:21:16 kilometer wide mountain of rock and ice
00:21:16 --> 00:21:18 will make its next close-up appearance
00:21:18 --> 00:21:20 in 2061.
00:21:20 --> 00:21:21 It's named in honor of the British
00:21:21 --> 00:21:25 astronomer Edmund Halley who in 1705
00:21:25 --> 00:21:26 after examining ancient Chinese,
00:21:26 --> 00:21:28 Babylonian, and medieval European
00:21:28 --> 00:21:30 records successfully predicted its
00:21:30 --> 00:21:32 return in
00:21:32 --> 00:21:36 1758. However, he died in 1742 before
00:21:36 --> 00:21:38 his prediction could be confirmed. The
00:21:38 --> 00:21:40 comet's highly elliptical and elongated
00:21:40 --> 00:21:42 orbit takes it from between the orbits
00:21:42 --> 00:21:44 of Mercury and Venus out almost as far
00:21:44 --> 00:21:47 as the orbit of Pluto. Hali's orbit is
00:21:47 --> 00:21:49 in retrograde, meaning it orbits the sun
00:21:49 --> 00:21:51 in the opposite direction to the
00:21:51 --> 00:21:53 planets, that is clockwise from above
00:21:53 --> 00:21:56 the sun's northern pole. This retrograde
00:21:56 --> 00:21:58 orbit results in it having one of the
00:21:58 --> 00:21:59 highest velocities relative to the Earth
00:22:00 --> 00:22:02 of any object in the solar system,
00:22:02 --> 00:22:06 traveling at some 70.56 km/s, or if you
00:22:06 --> 00:22:08 prefer,
00:22:08 --> 00:22:11 254 km hour, as well as the
00:22:11 --> 00:22:14 Etoacrids meteor shower every May. Hal's
00:22:14 --> 00:22:16 comet also produces the Orionids meteor
00:22:16 --> 00:22:19 shower in late October. Astronomers
00:22:19 --> 00:22:21 think comet Halley was originally a long
00:22:21 --> 00:22:23 period comet which took thousands of
00:22:23 --> 00:22:25 years to travel to the inner solar
00:22:25 --> 00:22:27 system from the ought cloud but was
00:22:27 --> 00:22:28 gravitationally perturbed into its
00:22:28 --> 00:22:30 current orbit by close encounters with
00:22:30 --> 00:22:33 the giant outer planets. The cloud is a
00:22:34 --> 00:22:36 hypothetical sphere of comets and
00:22:36 --> 00:22:38 asteroids beyond the heliosphere. a
00:22:38 --> 00:22:40 mixture of vagabonds from the solar
00:22:40 --> 00:22:43 system and objects from deep space which
00:22:43 --> 00:22:44 have been collected by the sun's
00:22:44 --> 00:22:47 gravitational pole. Occasionally, as the
00:22:47 --> 00:22:49 sun passes by another star, an orcloud
00:22:49 --> 00:22:51 object will get perturbed and be flung
00:22:51 --> 00:22:54 towards the inner solar system. The
00:22:54 --> 00:22:56 Acrid's meteor shower runs from the 19th
00:22:56 --> 00:22:59 of April through to the 28th of May,
00:22:59 --> 00:23:01 peaking around May the 5th with around
00:23:01 --> 00:23:04 55 meteors an hour, making it one of the
00:23:04 --> 00:23:05 southern hemisphere's best celestial
00:23:06 --> 00:23:09 showers. However, back in 1975, they
00:23:09 --> 00:23:12 were running 95 meteors an hour. And in
00:23:12 --> 00:23:16 1980, it was up to 110. Even better, the
00:23:16 --> 00:23:18 bright yellow meteors often appear as
00:23:18 --> 00:23:21 streaks known as trains. As their name
00:23:21 --> 00:23:23 suggests, they radiate out from the
00:23:23 --> 00:23:25 direction of the constellation Aquarius
00:23:25 --> 00:23:27 and the star Eta Aquiry. Just look
00:23:28 --> 00:23:29 towards the east after midnight and
00:23:29 --> 00:23:32 before dawn for the best view. And
00:23:32 --> 00:23:34 joining us now for the rest of our tour
00:23:34 --> 00:23:36 of the May night skies and skywatch is
00:23:36 --> 00:23:38 science writer Jonathan Alli. Good day
00:23:38 --> 00:23:40 Stuart. Yes, it's May. So the nights are
00:23:40 --> 00:23:42 definitely getting longer and colder in
00:23:42 --> 00:23:43 the part of the planet where I live as
00:23:43 --> 00:23:45 we head towards winter. But you know
00:23:45 --> 00:23:46 despite the cold, this is actually a
00:23:46 --> 00:23:48 great time for stargazing if you live
00:23:48 --> 00:23:49 where I am in the southern hemisphere as
00:23:49 --> 00:23:51 there are lots of great southern
00:23:51 --> 00:23:53 constellations visible. So some of the
00:23:53 --> 00:23:54 ones that you know you got to be far
00:23:54 --> 00:23:57 south to see such as the southern cross
00:23:57 --> 00:23:58 which at the moment is standing pretty
00:23:58 --> 00:24:00 much upright high in the south in the
00:24:00 --> 00:24:02 middle part of the evening to its left
00:24:02 --> 00:24:03 we've got these two bright stars in the
00:24:03 --> 00:24:06 constellation centurus that's alpha and
00:24:06 --> 00:24:08 beta centuri and astronomers call them
00:24:08 --> 00:24:10 the two pointers because if you draw an
00:24:10 --> 00:24:11 imaginary line between them and then
00:24:11 --> 00:24:13 keep the line going it more or less
00:24:13 --> 00:24:15 points towards the southern cross. Those
00:24:15 --> 00:24:16 two stars are really quite bright and
00:24:16 --> 00:24:18 prominent and they're close together. So
00:24:18 --> 00:24:20 people often spot them before they spot
00:24:20 --> 00:24:21 the southern cross. Yeah, I was using
00:24:21 --> 00:24:23 them as a marker to help me find the
00:24:23 --> 00:24:24 southern cross. Yeah. Yeah. And look,
00:24:24 --> 00:24:26 they're they're very bright compared to
00:24:26 --> 00:24:28 the the star. The stars in Southern
00:24:28 --> 00:24:30 Cross are not particularly dim, but it's
00:24:30 --> 00:24:32 a small constellation and when people go
00:24:32 --> 00:24:34 out try to find the southern cross, they
00:24:34 --> 00:24:35 um they're looking for something bigger.
00:24:36 --> 00:24:37 So, they don't really notice the cross
00:24:37 --> 00:24:38 at first. So, if you find these two
00:24:38 --> 00:24:39 pointer stars and then you just draw
00:24:40 --> 00:24:41 this do this trick of drawing the line
00:24:41 --> 00:24:43 and extending it a bit, then you think,
00:24:43 --> 00:24:44 "Oh, that's the southern that crosses
00:24:44 --> 00:24:46 it." So, uh yeah, they're very they're
00:24:46 --> 00:24:47 quite handy. Now, in the vicinity of the
00:24:47 --> 00:24:49 cross, there are two interesting sites
00:24:49 --> 00:24:50 to see, although you probably do need
00:24:50 --> 00:24:54 some non city dark skies to get a good
00:24:54 --> 00:24:55 view of them. The first of them is
00:24:55 --> 00:24:57 what's called the Cold Sack Nebula,
00:24:57 --> 00:24:59 which is a dark patch in the Milky Way
00:24:59 --> 00:25:01 right next to the Southern Cross. It's
00:25:01 --> 00:25:02 quite large. It's It's Yeah, it's
00:25:02 --> 00:25:03 probably about half the size or more of
00:25:03 --> 00:25:05 the Southern Cross. Yeah, this is quite
00:25:05 --> 00:25:07 large actually. It's a huge cloud of gas
00:25:07 --> 00:25:10 and dust almost 600 light years away.
00:25:10 --> 00:25:12 And because it's a very thick cloud of
00:25:12 --> 00:25:13 gas and dust, it's blocking out the
00:25:14 --> 00:25:16 light of the stars behind it. So, um,
00:25:16 --> 00:25:17 you know, years and years and years ago
00:25:18 --> 00:25:19 before photography started to come
00:25:19 --> 00:25:21 along, astronomers weren't really sure
00:25:21 --> 00:25:23 was this was this a hole in the Milky
00:25:24 --> 00:25:25 Way, and we're looking straight through
00:25:25 --> 00:25:28 to out to the other side, or is this a
00:25:28 --> 00:25:30 big dark something that's blocking the
00:25:30 --> 00:25:32 light from the stars behind? And yes, it
00:25:32 --> 00:25:35 is a big dark blob that is blocking the
00:25:35 --> 00:25:36 light of the stars behind it. There are
00:25:36 --> 00:25:38 stars in front of it, too, but not too
00:25:38 --> 00:25:40 many. They're not very um obvious to the
00:25:40 --> 00:25:42 naked eye. But you probably do need dark
00:25:42 --> 00:25:44 stars to see the um the Colac Nebula. I
00:25:44 --> 00:25:46 struggle to see it from where I am in
00:25:46 --> 00:25:48 suburbia. The other object of interest
00:25:48 --> 00:25:50 is a small star cluster called the jewel
00:25:50 --> 00:25:52 box, which is located a bit below and to
00:25:52 --> 00:25:54 the left of the leftmost star in the
00:25:54 --> 00:25:56 southern cross. Now, if you live in the
00:25:56 --> 00:25:58 city, you might just be able to make it
00:25:58 --> 00:25:59 out with your own eyes, but a pair of
00:25:59 --> 00:26:01 binoculars will definitely help. And
00:26:01 --> 00:26:02 through them, you'll see a pretty
00:26:02 --> 00:26:05 collection, maybe half a dozen, seven or
00:26:05 --> 00:26:07 eight, 10 stars perhaps, of different
00:26:07 --> 00:26:09 colors. That's why it's called a jewel
00:26:09 --> 00:26:10 box. And they're all closely packed
00:26:10 --> 00:26:12 together. All up, there are actually
00:26:12 --> 00:26:14 about a hundred stars in this cluster,
00:26:14 --> 00:26:15 but you're not going to see all of those
00:26:15 --> 00:26:17 with a pair of binoculars. You need big
00:26:17 --> 00:26:18 telescope to start see dozens and dozens
00:26:18 --> 00:26:20 of them. But it is really, really pretty
00:26:20 --> 00:26:21 and it's quite an easy one to see and
00:26:22 --> 00:26:23 it's fairly bright as star clusters go.
00:26:23 --> 00:26:25 That's much further away than the
00:26:25 --> 00:26:27 Colac's about 600 lighty years away.
00:26:27 --> 00:26:29 This little jewel box cluster is 6 and a
00:26:29 --> 00:26:32 half thousand light years away. Now to
00:26:32 --> 00:26:33 the right of the southern cross, as we
00:26:33 --> 00:26:35 look down to the south, you've got three
00:26:35 --> 00:26:36 large constellations. You've got Karina,
00:26:36 --> 00:26:39 VA, and Papus. all part of the Milky Way
00:26:39 --> 00:26:40 and they're full of glorious starfields
00:26:40 --> 00:26:42 and lots of nebulan things, including
00:26:42 --> 00:26:44 one called the Great Nebula in Karina.
00:26:44 --> 00:26:47 Now, this one rivals or in some people's
00:26:47 --> 00:26:50 opinions even exceed the splendor of the
00:26:50 --> 00:26:53 more famous nebula, the Orion Nebula,
00:26:53 --> 00:26:55 which is very easy to to make out
00:26:55 --> 00:26:57 because, you know, you can you need to
00:26:57 --> 00:26:58 see you need to be down south here to
00:26:58 --> 00:27:00 see the Karina. You got to be down south
00:27:00 --> 00:27:02 and it is a large fuzzy patch which you
00:27:02 --> 00:27:04 can see with your own eyes if you're
00:27:04 --> 00:27:06 under dark skies. But if you can get a
00:27:06 --> 00:27:08 telescope onto this region, uh, it just
00:27:08 --> 00:27:10 lets you see so much more. It really is
00:27:10 --> 00:27:13 is quite spectacular. It the extent of
00:27:13 --> 00:27:14 it, if you were able to see the whole
00:27:14 --> 00:27:16 thing with your just with your own eyes,
00:27:16 --> 00:27:18 it would be, you know, several times the
00:27:18 --> 00:27:20 width of the full moon. It's it's very
00:27:20 --> 00:27:22 large in the night sky. We don't notice
00:27:22 --> 00:27:25 it normally because it is fuzzy and
00:27:25 --> 00:27:28 faint. And most of us live in light
00:27:28 --> 00:27:31 polluted cities. So you you've got
00:27:31 --> 00:27:33 Buckley's chance as we say in Australia
00:27:33 --> 00:27:36 of seeing anything like this from light
00:27:36 --> 00:27:38 polluted light polluted skies. So you
00:27:38 --> 00:27:39 need to get somewhere dark and let your
00:27:40 --> 00:27:42 eyes get dark adapted. Now in the nearby
00:27:42 --> 00:27:44 constellation, same sort of well the
00:27:44 --> 00:27:45 other side of the cross really got
00:27:45 --> 00:27:47 centurus. You can find the globular star
00:27:47 --> 00:27:49 cluster Omega Centuri. Now this one is
00:27:49 --> 00:27:52 quite easy to see. It's visible as a
00:27:52 --> 00:27:54 just a what looks like a fuzgy star to
00:27:54 --> 00:27:57 the unaded eye. You got a pair of
00:27:57 --> 00:27:58 binoculars. It'll it'll reveal it
00:27:58 --> 00:27:59 depending on the size of your
00:27:59 --> 00:28:01 binoculars. It should reveal it to be
00:28:01 --> 00:28:04 like a small gray ball, just a tiny gray
00:28:04 --> 00:28:07 ball, but a telescope will show its true
00:28:07 --> 00:28:10 nature, which is a huge globe of
00:28:10 --> 00:28:13 seemingly countless stars, a globular
00:28:13 --> 00:28:14 star cluster, it's called it's called.
00:28:14 --> 00:28:16 It's an really impressive site. And if
00:28:16 --> 00:28:19 you get on the internet and have a look
00:28:19 --> 00:28:21 for Omega Centuri, you'll see what I
00:28:22 --> 00:28:23 mean. It is the most in fact, it's it's
00:28:23 --> 00:28:25 the best of these globular star clusters
00:28:25 --> 00:28:26 in the whole sky. It's the biggest and
00:28:26 --> 00:28:28 best and brightest. It really is very,
00:28:28 --> 00:28:31 very impressive. Now, low down in the
00:28:31 --> 00:28:32 eastern sky at mid evening, you got the
00:28:32 --> 00:28:34 constellation Scorpius above the
00:28:34 --> 00:28:37 horizon. This, for me, is a true
00:28:37 --> 00:28:38 indication that the middle of the year
00:28:38 --> 00:28:41 is upon us because Scorpius is us in the
00:28:41 --> 00:28:42 southern hemisphere a winter
00:28:42 --> 00:28:43 constellation. For our friends in the
00:28:43 --> 00:28:46 north, it's a summer constellation. So,
00:28:46 --> 00:28:48 as the evening goes on, the full extent
00:28:48 --> 00:28:50 of Scorpius will come up and and be
00:28:50 --> 00:28:52 visible. Scorpius is one of the rare
00:28:52 --> 00:28:53 constellations. It actually looks like
00:28:53 --> 00:28:55 what it's supposed to be. uh you know
00:28:55 --> 00:28:57 you've got triang constellation
00:28:57 --> 00:28:58 triangulum which is a triangle right so
00:28:58 --> 00:29:00 that's not too hard the southern cross
00:29:00 --> 00:29:02 does look like a southern cross but
00:29:02 --> 00:29:04 scorpius really does look like a
00:29:04 --> 00:29:05 scorpion it traces out the shape of a
00:29:06 --> 00:29:08 scorpion really really well it's it's
00:29:08 --> 00:29:09 just one of those things that just
00:29:09 --> 00:29:10 happen to be in the right part of the
00:29:10 --> 00:29:12 galaxy to see these stars from this
00:29:12 --> 00:29:14 point of view and uh yeah it really does
00:29:14 --> 00:29:16 the constellation right next to it
00:29:16 --> 00:29:18 famous Sagittarius got no idea what that
00:29:18 --> 00:29:19 looks like you know it's one of the join
00:29:19 --> 00:29:21 the dot things but when we do look at
00:29:21 --> 00:29:23 Sagittarius which was which we you will
00:29:23 --> 00:29:26 see if you stay past midnight, you'll
00:29:26 --> 00:29:27 see Sagittarius come up or if you wait
00:29:27 --> 00:29:28 for a month or two, it'll be in the
00:29:28 --> 00:29:30 evening sky. When we look towards
00:29:30 --> 00:29:32 Sagittarius, we are looking into the
00:29:32 --> 00:29:34 direction of the center of our Milky Way
00:29:34 --> 00:29:36 galaxy. And this is actually one of the
00:29:36 --> 00:29:39 main reasons why meteor stargazing is is
00:29:39 --> 00:29:40 considered so good by amateur
00:29:40 --> 00:29:42 astronomers because we have all the
00:29:42 --> 00:29:44 starfields and the deep sky objects of
00:29:44 --> 00:29:47 the Milky Way central region to enjoy
00:29:47 --> 00:29:48 because we're looking right into the
00:29:48 --> 00:29:50 core. There's lots and lots of stuff. If
00:29:50 --> 00:29:51 you look in the opposite direction,
00:29:51 --> 00:29:53 you're looking towards the outskirts of
00:29:53 --> 00:29:56 the galaxy and there's perhaps the left
00:29:56 --> 00:29:57 sea. So there's a lot of stuff
00:29:58 --> 00:30:00 concentrated in towards the center of
00:30:00 --> 00:30:02 our galaxy during the middle of the
00:30:02 --> 00:30:04 year. And because Sagittarius and it
00:30:04 --> 00:30:06 sort of surrounding constellations are
00:30:06 --> 00:30:07 located south of celestial equator, it
00:30:08 --> 00:30:09 means that those of us who live south of
00:30:09 --> 00:30:11 the earthly equator get the best view of
00:30:11 --> 00:30:13 it because from the latitude to where I
00:30:13 --> 00:30:15 live, it's basically right overhead at
00:30:15 --> 00:30:17 nighttime. So, you know, you when things
00:30:17 --> 00:30:18 are right overhead, you're looking
00:30:18 --> 00:30:19 through the thinnest part of the Earth's
00:30:19 --> 00:30:21 atmosphere. If things are down on the
00:30:21 --> 00:30:23 horizon, you're looking through a much
00:30:23 --> 00:30:24 greater extent of atmosphere, which
00:30:24 --> 00:30:26 makes the stars appear dimmer and and
00:30:26 --> 00:30:28 you get twinkling effects and the
00:30:28 --> 00:30:31 pollution and dust and whatever in the
00:30:31 --> 00:30:33 air. So, when you can see things up nice
00:30:33 --> 00:30:35 high, nice up nice and high, that's a
00:30:35 --> 00:30:37 whole lot better. So, our friends north
00:30:37 --> 00:30:38 of the equator can certainly see
00:30:38 --> 00:30:40 Sagittarius and Scorpius as well, but
00:30:40 --> 00:30:42 for them, it's lower down towards
00:30:42 --> 00:30:43 they're lower down towards the horizon.
00:30:44 --> 00:30:45 and it's still good, but nothing like
00:30:45 --> 00:30:47 being right underneath these particular
00:30:47 --> 00:30:49 constellations. Now, turning to the
00:30:49 --> 00:30:51 planets, Jupiter, it's big and bright.
00:30:51 --> 00:30:53 It's low down near the northwestern
00:30:53 --> 00:30:56 horizon after sunset. That's as we view
00:30:56 --> 00:30:58 it from the southern hemisphere during
00:30:58 --> 00:31:00 May. Now, make sure you take the
00:31:00 --> 00:31:02 opportunity to see it in the first two
00:31:02 --> 00:31:04 or three weeks of May because by the end
00:31:04 --> 00:31:05 of the month, it'll have disappeared
00:31:05 --> 00:31:07 into the twilight glow down on the
00:31:07 --> 00:31:09 northwestern horizon there. It's getting
00:31:09 --> 00:31:12 lower each night. Mars is quite easy to
00:31:12 --> 00:31:14 see in the northern half of the sky for
00:31:14 --> 00:31:15 us here in the south or southern half of
00:31:15 --> 00:31:17 the sky for our friends in the north.
00:31:17 --> 00:31:19 It's about halfway up from the horizon.
00:31:19 --> 00:31:21 It's in a fairly bare patch of sky, so
00:31:22 --> 00:31:24 it's intense ruddy color does make it
00:31:24 --> 00:31:26 stand out quite easily amongst all the
00:31:26 --> 00:31:28 stars that are around it. Now, the other
00:31:28 --> 00:31:29 three bright planets are all morning
00:31:29 --> 00:31:31 objects at the moment. It's visible out
00:31:31 --> 00:31:34 to the east before dawn. First up, we
00:31:34 --> 00:31:37 have Venus. It's extremely bright at the
00:31:37 --> 00:31:39 moment. You simply cannot miss it or
00:31:39 --> 00:31:41 mistake it for anything else. Just if
00:31:41 --> 00:31:42 you're up before dawn, look to the east,
00:31:42 --> 00:31:44 which is the direction that the sun
00:31:44 --> 00:31:46 comes up. And before the sun comes up,
00:31:46 --> 00:31:48 you see this big bright star looking
00:31:48 --> 00:31:50 thing in the sky. Well, that's Venus.
00:31:50 --> 00:31:52 That's uh there's nothing else like it.
00:31:52 --> 00:31:55 Not far from Venus, but quite a bit
00:31:55 --> 00:31:57 dimmer is another bright thing that
00:31:57 --> 00:31:58 looks like a star, but it's actually
00:31:58 --> 00:32:01 Saturn. And Saturn's fairly easy to spot
00:32:01 --> 00:32:03 because it's, you know, compared to
00:32:03 --> 00:32:05 other stars or compared to stars, it's
00:32:05 --> 00:32:06 reasonably bright. It's not bright
00:32:06 --> 00:32:08 compared to Venus, but it's bright
00:32:08 --> 00:32:10 enough. And it does have a yellowish
00:32:10 --> 00:32:12 sort of color to it. Uh about halfway in
00:32:12 --> 00:32:14 brightness between Saturn and Venus is
00:32:14 --> 00:32:16 Mercury. The planet Mercury, which is
00:32:16 --> 00:32:18 the innermost planet. Now, if you want
00:32:18 --> 00:32:20 to see Mercury, uh yes, you got you got
00:32:20 --> 00:32:22 to be up before dawn, but you also got
00:32:22 --> 00:32:24 to get out there and do it now because
00:32:24 --> 00:32:26 as the month goes on, you'll see Venus
00:32:26 --> 00:32:29 and Saturn still up fairly high, moving
00:32:29 --> 00:32:30 further apart from each other, but
00:32:30 --> 00:32:32 Mercury is going to start dropping down
00:32:32 --> 00:32:34 toward the horizon for night after
00:32:34 --> 00:32:35 night. By the end of the third week of
00:32:35 --> 00:32:39 May, it'll be lost in the glare of the
00:32:39 --> 00:32:42 uh dawn glory just before sunrise. So
00:32:42 --> 00:32:43 yeah, if you want to spot Mercury, if
00:32:43 --> 00:32:45 you've never seen it before, got to be
00:32:45 --> 00:32:47 up before dawn and got to do it in the
00:32:47 --> 00:32:49 next few weeks. And let's do Stewart is
00:32:49 --> 00:32:50 the sky formation. That's science writer
00:32:50 --> 00:32:54 Jonathan Nelly and this is Spaceime.
00:32:54 --> 00:33:08 [Music]
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