- The James Webb Telescope has discovered an ancient galaxy, called GS-9209, which suddenly and mysteriously died – halting all star formation.
- Inmarsat has denied suggestions that two recent outages of its I-4 F1 satellite was due to a denial of service cyber-attack by an unfriendly foreign power.
- - Queenslanders are on the hunt searching for meteorite fragments from a meteor which lit up the night skies of northern Queensland last week.
- - Procyon – the brightest star in Canis Minor, the bloated aging red giant Arcturus, the red super giant Antares, and the June solstice are among the highlights of the night skies on June Skywatch.
#space #astronomy #science #news #podcast #spacetime
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00:00:00
Stuart Gary: This is SpaceTime series 26 episode 66 for
00:00:03
broadcast on the second of June 2023. Coming up on space time,
00:00:09
an ancient galaxy suddenly dies. Inmarsat says Australian
00:00:14
satellite outages were not caused by cyber attacks and
00:00:18
northern Queensland residents rocked by a meteor all that and
00:00:22
more coming up on space time.
00:00:26
Generic: Welcome to space time with Stuart Garry.
00:00:46
Stuart Gary: Astronomers say they're stunned after the James
00:00:48
Webb space Telescope discovered an ancient galaxy called GS 9209
00:00:53
which suddenly and mysteriously died, halting all star
00:00:57
formation. The observations reported in the journal nature
00:01:00
suggest that the galaxy formed most of its stars during a
00:01:03
hyperactive starburst period between 600 million and 800
00:01:07
million years after the Big Bang 13.82 billion years ago.
00:01:11
But then just over 12.5 billion years ago, it suddenly stopped
00:01:15
making new stars. In fact, when the team observed it at 1.25
00:01:20
billion years after the Big Bang, no star formation had
00:01:23
taken place in the galaxy for around half a billion years.
00:01:28
The findings are surprising because here in our local
00:01:30
Universe, most massive Galaxies take billions of years to shut
00:01:34
down star formation despite being around 10 times smaller
00:01:37
than the milky way galaxy GS 92 9 has a similar number of stars.
00:01:42
These have a combined mass of around 40 billion times that of
00:01:46
our sun and were all formed rapidly before star formation in
00:01:50
the galaxy suddenly stopped.
00:01:52
Analysis also shows that like most if not all Galaxies GS 9200
00:01:56
and nine contains a super massive black hole at the
00:01:58
center. But interestingly, it's around five times larger than
00:02:03
what astronomers might anticipate for a galaxy of that
00:02:06
size.
00:02:07
And that could be the key astronomers think that the
00:02:10
supermassive black hole could be responsible for the sudden
00:02:14
shutdown of star formation if correct. The discovery provides
00:02:18
new insight in the processes involved in the early Universe's
00:02:21
star formation and the role which supermassive black holes
00:02:24
have in halting that formation.
00:02:27
You see the growth of supermassive black holes release
00:02:30
huge amounts of high energy radiation and that can heat up
00:02:34
gas, preventing it from collapsing and also push gas out
00:02:37
of Galaxies altogether. Either way you end up not having the
00:02:41
feed material needed for stellar formation. And so this could
00:02:45
have cause star formation in G S 92 oh nine to stop.
00:02:49
Webb's already shown that Galaxies were growing larger and
00:02:52
earlier than science had ever suspected. But this new work is
00:02:56
giving scientists a really detailed first look at the
00:02:58
properties of these early Galaxies charting in detail, the
00:03:02
history of Galaxies like G S 92 oh nine which managed to form as
00:03:06
many stars as our own milky way just 800 million years after the
00:03:10
Big Bang.
00:03:12
This is space time still to come. Imar Sat says a satellite
00:03:17
outage which affected much of Australia wasn't caused by cyber
00:03:21
attacks and the residents of North Queensland treated to a
00:03:25
spectacular meteor shower all that and more still to come on
00:03:29
space time.
00:03:45
Inmarsat has denied suggestions that two recent outages of its I
00:03:50
four F One satellite could have been due to denial of service
00:03:53
cyber attacks by an unfriendly foreign power. The British
00:03:57
commercial satellite operator says two recent failures of its
00:04:01
satellite which provides LBA services for Eastern Asia and
00:04:04
the Pacific region were due to a partial loss of power.
00:04:08
I four F One provides the South Pan satellite based augmentation
00:04:12
system which increases the accuracy of global satellite
00:04:15
navigation systems from a meter down to just centimeters. The
00:04:20
system supports services ranging from maritime safety operations
00:04:24
and aircraft navigation to farmers giving them improved
00:04:27
precision for crop sowing, fertilizing and spraying,
00:04:30
thereby reducing their costs and improving efficiency.
00:04:33
Imar says the sudden loss of power invoked automatic
00:04:37
procedures on the satellite that led to the suspension of
00:04:39
services while engineers are still investigating the cause of
00:04:43
the power loss. The London based company has ruled out space
00:04:46
debris or anything malicious such as a cyber attack. The I
00:04:50
four F One satellite was built by Eads Astrium which is now
00:04:54
part of Airbus defense and space using a Eurostar 300 GM bus.
00:04:59
The 5990 kg spacecraft was launched back in 2005 aboard an
00:05:04
Atlas five rocket space launch complex 41 at the Cape Canaveral
00:05:08
Space Force Base in Florida with an initial 13 year design life.
00:05:13
It's now been operating for 18 years. Imas says the Airbus
00:05:18
built I Six F One satellite launched in December 2021 is
00:05:22
slated to replace many of the I four F ONE S L BAND services in
00:05:26
coming weeks.
00:05:27
This is space time. Still to come. North Queensland residents
00:05:32
are treaded to a spectacular night show as a meteor lights up
00:05:35
their skies and pros the brightest star in Canis major,
00:05:40
the bloated aging red giant Atari, the super red giant
00:05:44
Antares and the June Solstice are among the highlights of the
00:05:48
night skies on June sky watch.
00:06:06
Queenslanders are on the hunt searching for meteorite
00:06:09
fragments from a meteor which lit up the night skies of
00:06:12
northern Queensland last week. A meter white space rock flashed
00:06:16
across the sky with a glowing green light seen from as far
00:06:20
south as Mackay north to Cairns and as far West as the Gulf Of
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Carpenter sightings were reported across the state with
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hundreds of people taking to social media to share videos.
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Astronomer Brad Tucker from the Australian National University
00:06:35
says the meteor was estimated to have been between half a meter
00:06:38
and a meter in size and it would have been traveling at 100
00:06:41
to 150 kilometers an hour.
00:06:44
Citizen scientists are now searching the outback for its
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landing site with the tiny golf town of Croydon ground zero.
00:06:52
That's because a sonic boom was felt by local residents at that
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location suggesting the meteor could have landed near the town.
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The sight boom itself would have actually been generated by shock
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waves as the meteor hit thicker layers of atmosphere and began
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fragmenting while most of it would have burnt up. Some larger
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fragments may have made it all the way down to the ground.
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Tucker says he's fairly certain the fireball was caused by a
00:07:16
meteor rather than space junk because Meteors have a
00:07:19
characteristic look, they're a bright solid light and they
00:07:22
often have a blue or green color. Tucker says a significant
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fraction of this meteor would have had bits of iron and nickel
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in it and it's that which would have caused it to glow blue
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green.
00:07:33
This is space time and time now to check out the night skies of
00:07:53
June on skywatch. June is the fourth month of the old Roman
00:07:57
calendar and he's named after Juno who was the wife of Jupiter
00:08:00
and also the equivalent to the Greek goddess Hera.
00:08:04
Another belief is that the month's name actually comes from
00:08:07
the Latin word EOR, which means younger ones. June is a great
00:08:12
time to look up at the night skies and marvel at the Majesty
00:08:15
Of The Milky Way, which puts on a spectacular overhead display.
00:08:18
This time of year. June also marks the winter solstice in the
00:08:23
southern hemisphere and summer solstice north of the equator,
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which this year happens at 12 57 in the morning of Thursday, June
00:08:30
the 22nd Australian Eastern Standard Time.
00:08:33
It's 10 57 in the morning of Wednesday, June, the 21st us
00:08:37
eastern daylight time and 2 57 in the afternoon, Greenwich.
00:08:41
Meantime, here in the southern hemisphere, it's the time of the
00:08:45
winter solstice and of course, it means the arrival of summer
00:08:48
for our lucky listeners north of the equator.
00:08:51
The June Solstice occurs when the sun reaches its most
00:08:53
northerly point in the sky as seen from Earth. Zenith
00:08:57
appearing to be directly over the tropic of cancer. Contrary
00:09:01
to popular belief that the seasons on Earth occur when the
00:09:04
Earth's orbit around the sun is at its nearest or furthest
00:09:07
points, they're actually governed by the tit of Earth's
00:09:10
axis as it journeys around the sun in a year.
00:09:13
So on the day of the June Solstice, the Earth's south pole
00:09:16
is tilted by 23 a half degrees away from the sun, the sun rises
00:09:21
north of east and sets north of West six months later, when the
00:09:24
south pole is tilted towards the sun, it's the southern
00:09:27
hemisphere summer and in between, we have the autumn and
00:09:30
spring equinoxes almost overhead.
00:09:34
This time of year, we have the constellation Virgo, the
00:09:37
constellations named after Virgo, the goddess of justice
00:09:41
and the harvest. In ancient Greek mythology who used her
00:09:43
scales to weigh good and evil.
00:09:46
However, she became so disenchanted with the evil deeds
00:09:49
of men, she threw away her scales and retreated to the
00:09:52
heavens. Interestingly, the ancient Egyptians also
00:09:55
associated Virgo with agriculture there.
00:09:58
She was the goddess Isis who sprinkled the heads of wheat
00:10:01
across the sky forming the milky way to science. Virgo is a
00:10:06
tightly packed region of space containing some 2000 Galaxies
00:10:10
all gravitationally bound into a gigantic galaxy cluster located
00:10:15
some 60 million light years away of which our local group of
00:10:18
Galaxies is simply an outlying member.
00:10:21
A light year is 10 trillion kilometers. The distance a
00:10:24
photon can travel in a year at the speed of light which is
00:10:27
about 300 kilometers per second in a vacuum.
00:10:30
And the ultimate speed limit of the Universe, the mass of the
00:10:34
Virgo supercluster is so enormous that its gravity
00:10:37
generates the so called Virgo centric flow causing our milky
00:10:41
way galaxy as well as Andromeda and all the other members of our
00:10:44
local group to move towards the supercluster at around 400
00:10:48
kilometers per second.
00:10:49
That's despite the accelerated expansion of the Universe over
00:10:52
cosmic timescales, the Virgo supercluster is now thought to
00:10:56
be nothing more than a lobe of an even bigger galaxy
00:10:59
supercluster known as Laak Kia. The center of which is known as
00:11:04
the Great Attractor, Lani AA and the Great Attractor are among
00:11:08
the largest known structures in the Universe.
00:11:12
Despite the Virgo cluster size, it's so far away. It's difficult
00:11:16
to see without a decent size backyard Telescope. You'll want
00:11:19
something at least 100 millimeters in diameter or
00:11:21
larger located right next to Virgo and directly overhead.
00:11:25
This time of year is the constellation Corvis. The Crow
00:11:29
Greek mythology tells us Corvis could talk to humans but he was
00:11:33
a lazy bird. And so Apollo took away his ability to speak and
00:11:38
banished him to the heavens.
00:11:40
One of the highlights in the constellations Virgo and Corvis
00:11:43
is the spectacular sombrero galaxy M 104 visible with a good
00:11:49
pair of binoculars or a small Telescope.
00:11:51
This stunning spiral galaxy is seen almost edge on providing a
00:11:55
spectacular backlit view of its galactic, bold stars and the
00:11:59
molecular gas and dust lanes in its arms M 104 is located some
00:12:04
31 million light years away and he's moving away from the milky
00:12:07
way at about 1000 kilometers per second. The sombrero galaxy has
00:12:12
a diameter of about 50 light years.
00:12:14
That's about 30% the size of our own galaxy. The milky way it's
00:12:18
surrounded by up to 2000 globular clusters and an active
00:12:22
central supermassive black hole at least a billion times the
00:12:25
mass of our sun.
00:12:27
Now, by comparison, Sagittarius, a star that's the supermassive
00:12:31
black hole at the center of the milky way has just 4.3 million
00:12:35
times the mass of the sun globular clusters are tight
00:12:39
balls containing millions of stars which were all either
00:12:42
originally formed at the same time from the same collapsing
00:12:45
molecular gas and dust cloud or they're the surviving cores of
00:12:48
small Galaxies that have been cannibalized by larger ones.
00:12:52
By the way, the brightest star in Virgo is Spiker a
00:12:55
spectroscopic binary located some 250 light years away.
00:13:00
Spectroscopic binaries are double star systems orbiting so
00:13:04
close to each other or at such an angle that they can't be
00:13:07
visually separated, at least not from our viewpoint on Earth.
00:13:11
Under these conditions. Their spectrum will actually be a
00:13:14
combination of the spectra of both of the stars in the system.
00:13:18
But as these stars orbit each other, one of the stars will be
00:13:22
moving sort of towards us, the other will be moving sort of
00:13:26
away from us. So the star moving towards us will have a spectra
00:13:30
that will be slightly blue shifted into high frequencies,
00:13:34
shorter wavelengths, will the star moving away from us will
00:13:37
have its spectra slightly red shifted to lower frequencies
00:13:41
longer wavelengths.
00:13:42
And so the two stars in the system can be separated by their
00:13:46
Doppler shift looking about 20 degrees above the western
00:13:50
horizon in the early evening is the fourth brightest celestial
00:13:53
object in the sky.
00:13:54
The dog star Sirius, only the sun, the moon and the planet
00:13:59
Venus look brighter to the north West or right of Sirius is
00:14:03
another fairly bright star called pros, the brightest star
00:14:07
at the constellation Canis Minor, the lesser dog in Greek
00:14:10
mythology, Canni Minor and Canis major were Orion's hunting dogs.
00:14:16
Peron is a binary star system comprising a spectral type F
00:14:20
main sequence white star proc A and a faint white dwarf
00:14:24
companion Peron B. Main sequence stars are those undergoing
00:14:29
hydrogen fusion into helium in their cause.
00:14:32
Astronomers describe stars in terms of special types, a
00:14:36
classification system based on temperature and characteristics.
00:14:40
The hottest most massive and most luminous stars are known as
00:14:43
spectra type O blue stars. They're followed by spectral
00:14:47
type B blue white stars, then spectral type A white stars,
00:14:50
spectral type F whitish yellow stars, spectral type G yellow
00:14:55
stars.
00:14:56
That's where our sun fits in spectra type K, orange stars.
00:15:00
And then the coolest and least massive of all stars are spectra
00:15:03
type M red stars commonly referred to as red dwarfs.
00:15:07
Each spectral classification is also subdivided using a numeric
00:15:11
digit to represent temperature with zero being the hottest and
00:15:14
nine, the coolest and a Roman numeral to represent luminosity.
00:15:19
Now put all that together and our sun is officially classified
00:15:23
as A G two V or G 25 yellow dwarf star.
00:15:27
Also included in the classification system are
00:15:30
spectral types L T and Y, which are assigned to failed stars
00:15:34
known as brown dwarves, some of which were actually born as
00:15:37
spectral type M red dwarf stars but became brown dwarves after
00:15:41
losing enough of their mass, brown dwarfs fit into a category
00:15:45
between the largest planets which are about 13 times the
00:15:48
mass of Jupiter and the smallest spectral type M red dwarf stars
00:15:52
which are around 75 to 80 times the mass of Jupiter or 0.8 solar
00:15:57
masses.
00:15:59
The white dwarf Proce Bee has about 0.6 times the mass of the
00:16:03
sun and a diameter of about 8600 kilometers.
00:16:08
A white dwarf is the stellar corpse of a sun like star having
00:16:12
used up its nuclear fuel supply fusing hydrogen into helium in
00:16:16
the main sequence. It then expands into a red giant and
00:16:20
begins fusing helium into carbon and oxygen stars like our sun
00:16:24
aren't massive enough to fuse carbon and oxygen into heavier
00:16:28
elements.
00:16:28
And so they turn off their attic gaseous envelopes flown off into
00:16:33
space as spectacular objects called artery nebula. What's
00:16:37
left behind is a super dense white hot stellar core about the
00:16:40
size of the Earth called a white dwarf which will slowly cool
00:16:45
over the eons of time located about 11.6 light years away.
00:16:50
Pro on a has about 1.5 times the mass of the sun and about twice
00:16:54
its radius. It also has about seven times the sun's luminosity
00:16:58
making it unusually bright for a star of this time. And that
00:17:02
suggests that it started to evolve off the main sequence.
00:17:05
After having fused nearly all of its core hydrogen into helium,
00:17:09
it means the star is about to expand into a sub giant as it
00:17:13
begins fusing core helium into carbon and oxygen and burning a
00:17:17
hydrogen in its outer shell as it continues to expand, the star
00:17:22
will eventually swell to somewhere between 80 and 100 and
00:17:25
50 times its current diameter.
00:17:27
It'll then become a red giant. This will probably happen within
00:17:31
the next 10 to 100 million years. The blink of an eye in
00:17:35
astronomical terms, the two stars prose on A and B orbit
00:17:40
each other every 40.82 Earth years at an average distance of
00:17:44
15 astronomical units about the distance of uranus orbit around
00:17:48
the sun.
00:17:49
An astronomical unit is the average distance between the
00:17:52
Earth and the sun, which is about 150 million kilometers or
00:17:55
8.3 light minutes looking to the north, north West now, and
00:18:00
you'll see the constellation Leo The Lion looking like a bunch of
00:18:04
stars shaped like an upside down question Mark located just 36.7
00:18:09
light years away.
00:18:10
And the constellation booties, the herdsman is ocurre a bloated
00:18:15
aging red giant about 7.1 billion years old and nearing
00:18:19
the end of its life, having used up all its core hydrogen.
00:18:23
It's now fusing helium into carbon and oxygen that's caused
00:18:27
the star, which is only slightly more massive than the sun to
00:18:30
expand outwards to around 25 times the sun's diameter and
00:18:34
become about 170 times as luminous, it'll soon puff off
00:18:38
its outer gasses envelope as a planetary nebula in the process
00:18:42
revealing its white hot stellar core.
00:18:45
In Greek mythology. Aus was the guardian of the bear. Now, this
00:18:50
is a reference to being next to the constellations, Ursa major
00:18:53
and Ursa minor. The greater and lesser bears. There's some
00:18:56
indications that auras could have a binary stellar companion,
00:19:01
but the results remain inconclusive, at least for.
00:19:03
Now, there's also speculation that it could have a large
00:19:07
platter or subs stellar object orbiting it something about 12
00:19:10
Jupiter masses in size. But again, the research remains
00:19:14
inconclusive looking to the east and you'll see the three
00:19:18
brightest stars in the constellation of Libra.
00:19:20
The scales of justice are visible about halfway about 40
00:19:23
degrees above the horizon. These also represent the claws of
00:19:27
Scorpius, the Scorpion which is chasing a rhine across the sky.
00:19:31
The brightest star in the constellation Scorpius is Alpha
00:19:34
Scorpion or Antares.
00:19:36
The Scorpion's heart easily seen with the unaided eye. This red
00:19:40
super giant is some 550 light years away and it's one of the
00:19:44
largest known stars in the Universe. Antares has about 18
00:19:48
times the mass and an incredible 883 times the diameter of the
00:19:53
sun and it's about 10 times more luminous than our sun too.
00:19:58
Ok. Turning to the southeast now and there you'll see the
00:20:01
constellation Sagittarius, the archer. It's important because
00:20:05
it marks the direction of the center of our galaxy, the milky
00:20:07
way and of course, located some 27 light years away in that
00:20:12
direction is the galaxy's central supermassive black hole
00:20:15
Sagittarius, a star to the ancient Babylonians.
00:20:19
Sagittarius was the God Norgle, the Centaur, a creature half man
00:20:23
and half horse. By the time Greek mythology took over
00:20:27
Sagittarius was carrying a bow loaded with an arrow and
00:20:30
pointing directly towards Antares, the heart of Scorpius,
00:20:33
the Scorpion, the center of the milky way and its supermassive
00:20:37
black hole Sagittarius, a star lie in the westernmost part of
00:20:41
Sagittarius.
00:20:43
The brightest star in Sagittarius is epsilon Sergei or
00:20:46
Co Australis, the southern part of the bow epsilon. Sergi is a
00:20:51
binary system located 100 and 43 light years away.
00:20:54
The primary star is an evolved spectra type e blue giant at the
00:20:58
end of its life on the main sequence, it is about 3.5 times
00:21:02
the sun's mass and about seven times its radius and is
00:21:06
radiating around 363 times the sun's luminosity.
00:21:10
It's also a very strong x-ray source and is spinning very
00:21:14
rapidly with an estimated radial velocity of some 236 kilometers
00:21:18
per second the system also displays an axis of infrared
00:21:22
radiation emissions suggesting the presence of a circumstellar
00:21:25
disc of dust. Now, the second star in the system appears to be
00:21:29
inside this debris disk, astronomers think it's a spectra
00:21:33
type g yellow dwarf star with about 95% the mass of the sun.
00:21:38
The second brightest star in Sagittarius is Sigma sari or the
00:21:42
name no is Babylonian. However, its meanings are known, it's
00:21:47
thought to represent the ancient Babylonian sacred city of Urdu
00:21:50
on the Euphrates River.
00:21:52
Now, if correct, they would make non, the oldest known star name
00:21:56
in current use non is a spectra type B blue star located about
00:22:00
260 light years away. It has about eight times the sun's mass
00:22:05
4.5 times its radius and about 3300 times the sun's luminosity
00:22:11
alphas, Agita or Ruck Bat, meaning the Arch's knee is a
00:22:14
spectral type B blue star located some 182 light years
00:22:19
away.
00:22:19
It has some 2.5 times the diameter of the sun and about 40
00:22:23
times the sun's luminosity. Astronomers think it's
00:22:26
surrounded by a dense debris disc and a newborn companion
00:22:30
star which is only now about to join the main sequence.
00:22:34
The Sagittarius constellation also hosts many star clusters
00:22:37
nebulae including some of the best known astronomical objects
00:22:41
in the sky.
00:22:42
These include the Lagoon Nebula messier eight, a spectacular
00:22:46
pink emission nebula located 5000 light years away and
00:22:50
measuring some 140 light years by 60 light years across the
00:22:55
central region of the Lagoon Nebula is also known as the
00:22:58
hourglass nebula because of its distinctive shape caused by a
00:23:01
matt propelled by a massive star forming region called Herschel
00:23:05
36 1 of the few star forming nebulae that it's possible to
00:23:09
see with the unaided eye.
00:23:11
The Lagoon Nebula was instrumental in the discovery of
00:23:14
Boch globules, more than 17 of which have been found in the
00:23:18
nebula. Astronomers think bulk globules contain embryonic proto
00:23:22
stars destined to eventually become new stellar generations.
00:23:26
Also located in this region of space is the stunning messy S 17
00:23:32
better known to pretty well everyone as the horsehead
00:23:34
nebula, it's located some 4890 light years away and is a dense
00:23:39
region of ionized atomic hydrogen, also known as the
00:23:43
Omega or Swan nebula. It banned some 15 light years across and
00:23:47
has about 800 times the mass of the sun.
00:23:50
It's considered one of the brightest and most massive star
00:23:52
forming regions in our galaxy. With the geometry similar to the
00:23:55
Orion nebula, except that it's being viewed edge on rather than
00:23:59
face on the open star cluster NGC 66 A lies embedded in the
00:24:05
nebulas and its gasses cause the nebula to shine due to the
00:24:09
intense radiation from its hot young stars.
00:24:13
Open star clusters are loosely bowing groups of stars usually
00:24:16
containing a few 100 to thousands. They're thought to
00:24:20
have originally all been formed in the same molecular gas and
00:24:23
dust cloud. But they're not as densely bound together as
00:24:26
globular clusters, open star clusters generally survive for a
00:24:30
few 100 million years where the most massive ones may be
00:24:33
surviving for a few billion.
00:24:35
Now, by contrast, the more massive globular clusters exert
00:24:38
such a strong gravitational attraction on their members.
00:24:41
They can survive for tens of billions of years or longer. The
00:24:44
nebula is thought to contain up to 800 stars.
00:24:47
More than 1000 additional stars are also being formed in the
00:24:50
surrounding molecular gas and dust clouds. It's also one of
00:24:54
the youngest known clusters with an age of just a million years.
00:24:58
The cloud of interstellar material which formed the nebula
00:25:01
is roughly 40 light years in diameter and it contains at
00:25:04
least 30 solar masses.
00:25:08
The trifid nebula messier 20 is another large star forming
00:25:11
emission nebula containing many young hot stars located between
00:25:16
11 light years away. The trifid nebula is a diameter of
00:25:20
around 50 light years. The outside of the trio is a bluish
00:25:24
reflection nebula.
00:25:26
While the inner region glows pink thanks to ionized hydrogen,
00:25:30
there are also two dark bands dividing the T Trafford nebula
00:25:33
into three regions or lobes hydrogen. In the nebula is being
00:25:37
ionized by a central triple star system which formed at the
00:25:41
intersection of the two dark bands creating its
00:25:44
characteristic pink color.
00:25:46
Another star forming region in this part of the sky is N G C
00:25:50
6559 located some 5000 light years away and containing both
00:25:55
red emission and blue reflection regions. Now, the grouping of
00:26:00
these three nebulae, the Lagoon Nebula, the trier nebula and G C
00:26:04
six double 59 is known as the Sagittarius triplet.
00:26:09
Another object worth looking out for is the red spider nebula N G
00:26:13
C 6537. It's a planetary nebula about 8000 light years away. It
00:26:19
has a prominent two lobe shape that could be due to a binary
00:26:22
companion or simply magnetic fields and it has a fascinating
00:26:26
s shaped symmetry with the lobes opposite each other appearing
00:26:29
similar.
00:26:30
Again, this is believed to be due to the presence of a
00:26:33
companion star to the central white dwarf. As for the central
00:26:37
white dwarf, the remnant of the original star, it produces a
00:26:40
powerful 10 degree hot 3000 kilometer per second stellar
00:26:45
wind which is generating 100 billion kilometer high waves
00:26:50
from supersonic sharks formed as the local gas is being
00:26:53
compressed and heated in front of the rapidly expanding lobes.
00:26:57
Atoms caught up in these shocks are red, adding in visible light
00:27:01
giving the nebula its unique spider like shape and also
00:27:04
contributing to the nebula's expansion.
00:27:07
The star at the center of the red spider nebula is surrounded
00:27:10
by a dust shell making its exact properties hard to determine its
00:27:15
surface temperature is probably somewhere around 250
00:27:18
degrees. Although a temperature of up to half a million degrees
00:27:21
can't be ruled out, which would make it among the hottest white
00:27:24
dwarf stars known.
00:27:27
Now, looking directly south right now, you'll see the star
00:27:30
polaris australis or more accurately, Sigma Octus.
00:27:34
It's the nearest start of the southern celestial pole and
00:27:37
consequently the counterpart to the northern star polaris.
00:27:41
However, Sigma Oc Tanti is far harder to see than polaris as
00:27:44
it's much fainter located some 270 light years away. It's an
00:27:49
orange giant reaching the end of its life.
00:27:52
Now turning to the southwest and just above the horizon, you'll
00:27:55
see the star Canopus. It's the second brightest star in the
00:27:59
night sky after Sirius Canopus is located some 310 light years
00:28:03
away and is the brightest star at the constellation Karina. The
00:28:06
keel Canopus is a super giant some nine times the mass of the
00:28:10
sun and 71 times its diameter.
00:28:14
The month of June also marks the first of two annual encounters
00:28:18
with the Torres meteor shower. The Torres are generated as the
00:28:22
Earth passes through the debris stream created by the comet two
00:28:25
P Anke, which itself could be part of a larger comet which
00:28:29
broke apart about 20 to 30 years ago.
00:28:32
Most likely following numerous interactions with the powerful
00:28:35
gravitational field of the planet Jupiter as their name
00:28:38
suggests the torre's radiant or apparent point of origin is in
00:28:43
the constellation Tous, the ball, the torrent's meteor
00:28:46
shower is made up of large or massive material, think of
00:28:50
pebbles instead of dust grains, Earth passes through the stream
00:28:54
twice every year.
00:28:55
Once in June, then again in October where it's called the
00:28:58
Halloween fireballs. The tours releases material birth by
00:29:02
normal cometary activity and also occasionally by close
00:29:06
encounters with the tidal gravitational force of the Earth
00:29:09
and other planets.
00:29:11
Now, all this combines to make the torrid stream of material
00:29:14
the largest in the inner solar system. And since the meteor
00:29:18
stream is rather spread out in space, the Earth will take
00:29:21
several weeks to pass through it causing an extended period of
00:29:24
meteor activity compared with the much smaller periods of
00:29:27
activity for other meteor showers.
00:29:30
Now included in the turret stream is a denser flow of
00:29:33
gravelly meteoroids called the Torit swarm. It's thought to be
00:29:37
a ribbon of rocks, roughly 75 million kilometers wide by 100
00:29:41
and 50 kilometers across and held in orbit by Jupiter's
00:29:44
gravity. Now, occasionally the Earth will pass through some of
00:29:47
the larger meteoroids in the denser Torit swarm. And that can
00:29:51
make things rather interesting on Earth.
00:29:54
In fact, one of the larger chunks of the turrets swarm is
00:29:57
now thought to have been the cause of the infamous Tanggu
00:30:00
meteor event in the skies over Siberia on June, the 30th 19 oh
00:30:04
eight The Tagus Event is now believed to have been the air
00:30:07
burst of a 100 m wide meteor over the Tagus region of Russia
00:30:12
causing mass devastation and flattening more than 2000 square
00:30:16
kilometers of forest into matchsticks.
00:30:19
In fact, the blast was so bright. It lit up the skies in
00:30:22
London, a third of the way around the planet Togusa remains
00:30:27
the largest known Earth impact event in recorded history. It
00:30:31
was considered a one in 1000 year event assuming a random
00:30:34
distribution of events over time.
00:30:36
But new studies suggest the event may have been caused by a
00:30:39
torrid swarm meteor and with Earth passing through the swarm
00:30:43
periodically, it changes the odds significantly. Now, if this
00:30:47
study is correct, the swarm heightens the possibility of a
00:30:50
cluster of large impacts on Earth over a relatively short
00:30:53
period of time for the complicating matters. The gene
00:30:56
Toros are actually seen as two separate showers.
00:31:00
The southern Toros are the ones associated with the comet two P
00:31:03
Anke. While the northern Toros originate from the asteroid 2004
00:31:07
T G 10, an eccentric kilometer wide asteroid classified as a
00:31:12
near Earth object and a potentially hazardous asteroid
00:31:14
of the Apollo group. Jonathan Nally is the editor of
00:31:18
Australian Sky and Telescope Magazine. He joins us now for
00:31:22
the rest of our tour of the June night skies.
00:31:24
Jonathan Nally: Good day Stewart. Well, yeah, it's June.
00:31:26
So for us in the southern hemisphere down here where I
00:31:29
observe from, we've got the galaxy, our milky way stretching
00:31:32
across the sky from the east to the West at this time of year in
00:31:35
the sort of early evening when it's nice and dark down here
00:31:39
because it's winter time.
00:31:40
So, yeah, milky way, stretching all the way across the sky from
00:31:42
the east to the West. We've got the southern cross down here in
00:31:44
the south. It's about two thirds of the way up from the horizon,
00:31:47
from the southern horizon and pretty much upright. It looks a
00:31:50
bit like a kite and it's pretty easy to see because most of its
00:31:53
stars are nice and bright over in the West just above the
00:31:55
horizon.
00:31:56
You've got the brightest star in the night sky Sirius, but it's
00:31:59
about to disappear. It'll give it another few weeks and it'll
00:32:03
be below the western horizon after sunset. So it'll be gone
00:32:07
for this season around to the left of Sirius in the sort of
00:32:10
south western part of the sky. We've got the second brightest
00:32:12
star in the night sky that's called Canopus.
00:32:14
And it's in the constellation Karina. If you in a dark
00:32:17
location with clear skies and you can get a good view of the
00:32:21
southern horizon, have a look to the south and see if you can
00:32:23
spot the two Magellanic cloud Galaxies. Now, these Galaxies
00:32:27
are quite large but they're very faint. They look like dull
00:32:30
smudges or clouds.
00:32:32
That's why they call the Magellanic cloud because
00:32:34
Magellan spotted them and thought, oh, what are those
00:32:36
clouds up there in the sky? And they didn't move. So obviously,
00:32:38
they're not clouds. They're actually Galaxies, tens of
00:32:41
thousands of light years away from it. So they are the nearest
00:32:43
sizable Galaxies to our own.
00:32:45
So if you've got some good dark skies, as they say, you can look
00:32:47
down to the south and see if you can spot these two Galaxies,
00:32:49
One's bigger and one's more, you've got the large Malan cloud
00:32:52
and the small Malan cloud up in the northern half of the sky,
00:32:54
the sky seems a little bit bare this time of the year, but
00:32:57
there's a couple of bright stars, there's a bright star
00:32:59
called Arch Tous, which can be seen about half way up from the
00:33:01
northern horizon, much higher, almost overhead.
00:33:04
In fact, there's another bright star called Spiker. Now, Arc
00:33:07
Tous is a red giant star that's a couple of billion years older
00:33:10
than our sun. It's the same mass as the sun. It has ballooned up
00:33:13
to be about 25 times bigger because it's older when, when
00:33:17
these sort of stars get old, they enlarge.
00:33:20
So this one's 25 times bigger than ours. And at the moment,
00:33:23
Spiker, the other star I mentioned it's a binary star
00:33:25
system and a pair of stars in this system orbit each other so
00:33:29
closely that it only takes four days to go around each other and
00:33:32
their mutual gravitational pull has stretched each of these
00:33:36
stars from a round shape into an egg shape with a pointy bit
00:33:40
pointing towards each each other.
00:33:41
So that's pretty amazing. I mean, two massive stars. Can you
00:33:43
imagine that orbiting around each other? Only taking four
00:33:45
days?
00:33:46
Honestly, some of the things that are out there in space are
00:33:49
pretty mind blowing. And we live in a fortunately very sedate,
00:33:53
quiet soul of this where these sort of things don't happen.
00:33:56
Otherwise, we might be in trouble. Now, as the night goes
00:33:59
on, you'll see that things have changed as the Earth is turning
00:34:02
by midnight.
00:34:02
As I say, Sirius has gone in the West in the north, we've got the
00:34:05
bright stars, Vega and alta have appeared and in the South East,
00:34:09
we've got site called Ana, which is started to the end of a
00:34:12
really long constellation with no other bright stars around it.
00:34:15
So it sort of sticks out like a sore thumb. So it's pretty easy
00:34:17
to spot. And the milky way which was stretching from east to West
00:34:20
across the sky is now stretching basically from north to south.
00:34:24
That's because the Earth has turn on.
00:34:26
So things that were below the horizon a few hours ago have now
00:34:29
come up into view over the eastern horizon and things that
00:34:31
were visible in the western sky disappearing from view as they
00:34:35
go down below the western horizon. Now, let's look at the
00:34:38
planets, the innermost planet Mercury is pretty much out of
00:34:40
view at the moment.
00:34:41
You really won't have any chance of spotting it because Mercury
00:34:43
orbits so close to the sun, it doesn't appear very far from the
00:34:47
sun in the sky. When we have a look at it, start that again
00:34:51
because Mercury orbits so close to the sun, it doesn't appear
00:34:55
very far from the sun when we look for it in the sky.
00:34:58
So at the moment, its orbit is taking it around to the other
00:35:01
side of the sun from us. And so it's lost in the solar glare.
00:35:04
It'll be back next month though. Venus is very easy to see at the
00:35:07
moment. If you go out and look to the West after sunset, you
00:35:10
just won't miss it unless you've got cloudy skies.
00:35:12
But if you've got nice clear skies, you'll just see this big
00:35:15
bright, bold star looking thing, but that's the planet Venus and
00:35:20
you won't mistake it for any other stars around because it is
00:35:22
much brighter, the biggest brightest things out there other
00:35:26
than the moon.
00:35:26
Stuart Gary: The thing about planets, they don't twinkle like
00:35:29
stars do in the night sky do.
00:35:30
Jonathan Nally: They, they don't twinkle like stars when they're
00:35:34
a reasonable elevation above the horizon. The common explanation
00:35:37
for that is that stars are so far away that they are
00:35:40
effectively a point, they're effectively a tiny point of
00:35:44
light and that light that's coming through, our atmosphere
00:35:46
gets disrupted and disturbed and broken up by the air currents in
00:35:50
our atmosphere.
00:35:50
Whereas the planets, even though they appear to be tiny dots of
00:35:54
light as well, they do actually have a discernible size and that
00:35:57
helps compensates for the twinkling effect.
00:36:01
But if the planet is way down low just above the horizon, then
00:36:05
they do seem to twinkle, they can see the twinkle. There have
00:36:07
been plenty of incidents. I mean, I had a friend ring me up
00:36:09
once.
00:36:10
I said there's this red light, I've been going out every night
00:36:12
and there's this red light out over the ocean from where I live
00:36:15
and it's winking and blinking and I don't know what the air
00:36:17
force is doing out there or UFO or whatever it is.
00:36:20
So I quickly check my software that's MARS and because it's so
00:36:25
low down on the horizon, it's having to shine through more
00:36:28
atmosphere sort of coming sideways towards us than it
00:36:31
would if it was directly overhead where you're going
00:36:33
through less atmosphere.
00:36:34
So, yes, the planets can twinkle if they're low down and it
00:36:37
relates to all sorts of UFO reports and other things and
00:36:41
also not so much a twinkling effect, but people have been
00:36:44
startled for instance by Venus just talking about Venus.
00:36:48
You know, when you're driving along a road and you go an
00:36:50
avenue of trees on one side or either side that are carefully
00:36:54
spaced apart, you can get a sort of a strobe effect. If there's
00:36:56
anything on the other side of it. Yeah. Well, that, that can
00:37:00
really fool the eye and the mind.
00:37:03
And I recall one report of a woman driving along and there
00:37:05
was this big bright light out to the side and she was driving
00:37:08
through an avenue of trees and just the optical effects made it
00:37:11
trick her into thinking this light was following her.
00:37:14
Whereas it wasn't, it was just this sort of optical illusion
00:37:16
you get when you drive through an avenue of trees with a light
00:37:19
out, it's very easy to be fooled by things you're not expecting
00:37:24
to see. And if you don't quite know what they are, that's why
00:37:26
we do have a lot of so called UFO reports.
00:37:28
Now, Venus, ok. We're talking about Venus, but up higher than
00:37:30
Venus, if you go out and look for Venus, you can't miss it.
00:37:32
Big, bright white thing. If you look up above Venus, you'll see
00:37:36
what looks like a medium brightness, reddish star. This
00:37:40
is what we were just talking about.
00:37:41
It's not actually a star, it's the planet Mars. Ok. So you
00:37:44
won't see a twinkling most likely, but it's not very big
00:37:46
and it's not super bright, sort of medium brightness.
00:37:49
Now, keep an eye on both Venus and Mars over the next few weeks
00:37:52
and you'll see them get closer and closer and closer together.
00:37:55
And by the end of the month they'll be really close together
00:37:58
as we see them from Earth. They're not close together
00:38:00
actually in space. Of course, it's just a line of side effect.
00:38:03
But if you do have good weather over the next few weeks, go out
00:38:05
just five minutes each evening if you can and just look at
00:38:09
Venus and look at Mars and just compare their positions night
00:38:12
after night, after night and you'll see that they're slowly
00:38:14
drawing together and that's just these planets going around in
00:38:17
their orbits and us going around in our orbit and getting a
00:38:20
changing perspective line of sight perspective from where we
00:38:23
are.
00:38:24
So you can actually really not seeing it in real time as such.
00:38:27
But if you call it night after night, real time, I guess you
00:38:29
can say that night after night we're seeing in real time the
00:38:32
dance of the planets around the sun.
00:38:35
So that's really fun to do, you know, particularly you take one
00:38:37
of your kids outside and say, look, that's Venus, it's Mars
00:38:40
and let's go out like a couple of nights from now or next week
00:38:43
and see how they've changed. It really is quite nice to see that
00:38:46
the things up in the sky are not static or some things are not
00:38:49
static. At least the planets do move a nice walk.
00:38:52
Yeah, you're out walking the dog or whatever, just look up. Most
00:38:55
people don't look up too much, you know, so just look up and
00:38:58
have a look at the sky and you see there's lots of good things
00:38:59
to see, one of which will be Saturn.
00:39:02
Now, Saturn can be seen rising over the eastern horizon about
00:39:06
an hour before midnight, start of June and take a look on the
00:39:09
10th 10th of June. If you're having trouble spotting which
00:39:11
one is Saturn and you'll see that the moon is very close to
00:39:14
it. So if you go out and see the moon can't miss the moon, the
00:39:17
bright star in inverted commas near it is actually the planet
00:39:20
Saturn.
00:39:21
It has a slightly yellowish sort of tinge and the last one,
00:39:25
Jupiter, if you want to see Jupiter, or you're going to have
00:39:27
to be a bit of a real night owl or a very early riser because
00:39:30
coming up over the eastern horizon about an hour or so an
00:39:34
hour and a half before dawn. Ok.
00:39:36
So if you're up early or you pulling an all nighter, you
00:39:41
might be able to go outside before you go to bed. Have a
00:39:43
look for Jupiter. You can't miss just like Venus. It too is big
00:39:47
and bright. I think it's a bit brighter than Saturn at the
00:39:49
moment.
00:39:49
Saturn two is quite bright, but Jupiter and Venus typically are
00:39:52
very, very bright so you won't be able to miss it. My eyes see
00:39:56
Jupiter is pretty much white ish, but Saturn has a definite
00:40:00
yellow tinge. Mars is definitely a ruddy reddish orange, Venus is
00:40:06
generally bright white and so is Mercury, but it does depend on
00:40:10
your eyes.
00:40:10
It depends on whether you're looking through air pollution.
00:40:13
It depends on the planet's down low or up high because, you
00:40:16
know, certain wavelengths draw by the atmosphere, particularly
00:40:19
when they're down low. So that's actually a good test to go
00:40:21
outside with someone, you know, and say, ok, what color do you
00:40:24
see?
00:40:24
And in fact, because our eyes, if it's night time and there are
00:40:28
no lights around, everything's dark, our eyes are using the
00:40:30
part of the retina that is good for picking up low light levels,
00:40:34
but it is not really good at color. That's why things mostly
00:40:36
seem black and white at night because light is everything's
00:40:39
pretty dim at night.
00:40:40
Whereas during the daytime, when everything is nice and bright,
00:40:43
we don't have any trouble seeing color. And that reminds me
00:40:46
actually of the famous scientist George Gamma. His famous thing
00:40:49
about, he proved scientifically that the moon is better than the
00:40:53
sun.
00:40:54
Did you know this? He actually, he actually proved that the moon
00:40:56
is better than the sun because he said the moon shines at night
00:40:59
time and it gives us illumination when everything is
00:41:02
dark, which is really handy you see, but the sun, well, it only
00:41:05
shines during the daytime when it's light.
00:41:06
Stuart Gary: Anyway, that's Jonathan Ally, the editor of
00:41:11
Australian Sky and Telescope Magazine. This is space time and
00:41:31
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