Welcome to Astronomy Daily, bringing you the latest space and astronomy news. I'm Anna, joined by my co-host Avery, with today's cosmic headlines for Wednesday, February 4th, 2026.
Episode Highlights:
🚀 ARTEMIS 2 DELAYED - NASA's historic moon mission pushed to March after hydrogen leak during wet dress rehearsal. Four astronauts await their journey around the Moon as teams address familiar technical challenges.
🛰️ SPACEX UNVEILS STARGAZE - Revolutionary space traffic management system uses 30,000 star trackers to detect 30 million orbital transits daily. Free conjunction data offered to all satellite operators starting this spring.
⚠️ FALCON 9 GROUNDED - SpaceX temporarily halts launches after upper stage deorbit issue. Critical Crew-12 astronaut mission scheduled for February 11th hangs in the balance.
🌌 JWST'S RARE DISCOVERY - Five-way galaxy merger spotted in early universe challenges cosmic evolution models. System formed just 800 million years after Big Bang shows unexpected complexity.
🌠 LOCAL VOID MYSTERY SOLVED - 50-year puzzle resolved as scientists map flat sheet of matter beyond Local Group. Milky Way fleeing massive cosmic void at 600,000 mph.
⭐ RUNAWAY STARS MAPPED - Largest study reveals dual mechanisms ejecting massive stars from the galaxy. 214 O-type stellar speedsters analyzed, some exceeding 700 km/s.
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00:00:00 --> 00:00:02 Welcome [music] to Astronomy Daily, your
00:00:02 --> 00:00:04 source for the latest space and
00:00:04 --> 00:00:06 astronomy news. I'm Anna. [music]
00:00:06 --> 00:00:08 >> And I'm Avery. We're here to bring you
00:00:08 --> 00:00:10 today's cosmic headlines on this
00:00:10 --> 00:00:13 Wednesday, February 4th, 2026.
00:00:13 --> 00:00:15 >> We've got a packed [music] show today
00:00:15 --> 00:00:17 with some significant developments.
00:00:17 --> 00:00:19 NASA's Aremis 2 mission [music] has hit
00:00:19 --> 00:00:21 another speed bump with their moon
00:00:21 --> 00:00:23 rocket experiencing some familiar issues
00:00:23 --> 00:00:26 during testing. SpaceX is making
00:00:26 --> 00:00:28 headlines [music] on two fronts today.
00:00:28 --> 00:00:30 Launching an innovative new space safety
00:00:30 --> 00:00:32 system while also dealing with a
00:00:32 --> 00:00:33 temporary [music] grounding of their
00:00:33 --> 00:00:36 Falcon 9 rocket. The James Web Space
00:00:36 --> 00:00:38 Telescope has spotted something [music]
00:00:38 --> 00:00:40 extraordinary in the early universe. A
00:00:40 --> 00:00:43 rare fiveway galaxy merger that's
00:00:43 --> 00:00:45 challenging our understanding of cosmic
00:00:45 --> 00:00:46 evolution.
00:00:46 --> 00:00:47 >> Scientists have finally cracked [music]
00:00:47 --> 00:00:50 a 50-year mystery about why nearby
00:00:50 --> 00:00:52 galaxies seem to be fleeing from us.
00:00:52 --> 00:00:54 [music] and it involves a massive cosmic
00:00:54 --> 00:00:55 void.
00:00:55 --> 00:00:57 >> And we'll wrap up with fascinating new
00:00:57 --> 00:00:59 [music] research on runaway stars.
00:00:59 --> 00:01:02 Massive stellar objects racing through
00:01:02 --> 00:01:04 the Milky Way at incredible speeds.
00:01:04 --> 00:01:05 >> Let's dive in.
00:01:06 --> 00:01:07 >> Our [music] top story today comes from
00:01:07 --> 00:01:10 NASA's Kennedy Space Center in Florida,
00:01:10 --> 00:01:12 where Artemis 2 mission has been delayed
00:01:12 --> 00:01:14 by at least a month following issues
00:01:14 --> 00:01:16 during a critical wet dress rehearsal
00:01:16 --> 00:01:17 test.
00:01:17 --> 00:01:19 >> This is the mission that will send four
00:01:19 --> 00:01:21 astronauts on a flyby of the moon. the
00:01:21 --> 00:01:23 first crude lunar mission in over 50
00:01:23 --> 00:01:26 years. The crew includes NASA astronauts
00:01:26 --> 00:01:29 Reed Weisman, Victor Glover, Christina
00:01:29 --> 00:01:31 and Canadian Space Agency
00:01:31 --> 00:01:33 astronaut Jeremy Hansen.
00:01:33 --> 00:01:35 >> So, what happened during this test? NASA
00:01:36 --> 00:01:38 concluded a 49-hour practice countdown
00:01:38 --> 00:01:41 on Tuesday after loading 700 gallons
00:01:41 --> 00:01:44 of liquid hydrogen and liquid oxygen
00:01:44 --> 00:01:46 into the massive space launch system
00:01:46 --> 00:01:48 rocket. And early in the tanking
00:01:48 --> 00:01:51 process, as we reported yesterday, they
00:01:51 --> 00:01:52 detected a hydrogen leak from the
00:01:52 --> 00:01:54 interface that routes cryogenic
00:01:54 --> 00:01:57 propellant into the rocket's core stage.
00:01:57 --> 00:01:58 Sound familiar?
00:01:58 --> 00:02:01 >> Unfortunately, yes. These hydrogen leaks
00:02:01 --> 00:02:02 are reminiscent of the issues that
00:02:02 --> 00:02:04 plagued the Aremis 1 launch attempts
00:02:04 --> 00:02:07 back in 2022. However, there's some good
00:02:07 --> 00:02:09 news. They did resolve the issue during
00:02:09 --> 00:02:11 this test and actually achieved full
00:02:12 --> 00:02:14 tanking on the first try, which NASA
00:02:14 --> 00:02:17 considers a tremendous success. That's
00:02:17 --> 00:02:19 actually quite significant progress. The
00:02:19 --> 00:02:21 resolution involved stopping the
00:02:21 --> 00:02:23 hydrogen flow, allowing the interface to
00:02:23 --> 00:02:25 warm up so the seals could recede, and
00:02:25 --> 00:02:28 then adjusting the flow of propellant.
00:02:28 --> 00:02:30 It worked, but it raised concerns about
00:02:30 --> 00:02:31 launch day operations.
00:02:32 --> 00:02:34 >> NASA administrator Jared Isaacman
00:02:34 --> 00:02:35 announced they're moving off the
00:02:36 --> 00:02:38 February launch window and targeting
00:02:38 --> 00:02:40 March for the earliest possible launch.
00:02:40 --> 00:02:42 The first opportunity next month is
00:02:42 --> 00:02:45 Friday, March 6th at 8:29 p.m. Eastern
00:02:46 --> 00:02:47 time with the window extending through
00:02:47 --> 00:02:50 March 11th. There were other issues,
00:02:50 --> 00:02:52 too, weren't there? I read about
00:02:52 --> 00:02:53 problems with a valve and some
00:02:53 --> 00:02:55 communication dropouts.
00:02:55 --> 00:02:58 >> Right. A valve associated with the Orion
00:02:58 --> 00:03:00 crew module hatch pressurization had to
00:03:00 --> 00:03:03 be retored, and closeout operations took
00:03:03 --> 00:03:05 longer than planned. Cold weather
00:03:05 --> 00:03:07 affected several cameras and other
00:03:07 --> 00:03:09 equipment. And perhaps most concerning,
00:03:09 --> 00:03:11 there were dropouts in audio
00:03:11 --> 00:03:13 communication channels that have been
00:03:13 --> 00:03:15 recurring over the past few weeks.
00:03:15 --> 00:03:17 >> What's the crew saying about all this?
00:03:17 --> 00:03:19 >> Commander Reed Wisman posted on social
00:03:19 --> 00:03:22 media expressing immense pride in seeing
00:03:22 --> 00:03:25 the rocket reach 100% fuel load,
00:03:25 --> 00:03:27 especially knowing how challenging the
00:03:27 --> 00:03:29 scenario was for the launch team. He
00:03:29 --> 00:03:30 said they're jumping back into training
00:03:30 --> 00:03:32 tomorrow to start preparations for
00:03:32 --> 00:03:33 March.
00:03:33 --> 00:03:35 >> And NASA's planning another wet dress
00:03:35 --> 00:03:37 rehearsal before the actual launch.
00:03:37 --> 00:03:37 Correct.
00:03:37 --> 00:03:39 >> That's right. Launch director Charlie
00:03:39 --> 00:03:41 Blackwell Thompson confirmed they'll
00:03:41 --> 00:03:43 conduct another wet dress before
00:03:43 --> 00:03:45 proceeding with the actual launch. The
00:03:46 --> 00:03:48 team needs to fully review all the data
00:03:48 --> 00:03:50 from this test, mitigate each issue, and
00:03:50 --> 00:03:52 return to testing before setting an
00:03:52 --> 00:03:54 official target launch date.
00:03:54 --> 00:03:56 >> It's a delay, but safety has to come
00:03:56 --> 00:03:58 first, especially with a crude mission
00:03:58 --> 00:04:01 to the moon. From the moon to low Earth
00:04:01 --> 00:04:04 orbit, SpaceX has just unveiled a
00:04:04 --> 00:04:06 revolutionary new space safety system
00:04:06 --> 00:04:09 called Stargaze that could fundamentally
00:04:09 --> 00:04:11 change how we manage the increasingly
00:04:12 --> 00:04:14 crowded space around our planet. This is
00:04:14 --> 00:04:17 fascinating technology, Anna. Stargaze
00:04:17 --> 00:04:19 is a space situational awareness system
00:04:19 --> 00:04:22 that uses data from nearly 30 star
00:04:22 --> 00:04:24 trackers across the Starlink satellite
00:04:24 --> 00:04:26 constellation to continuously monitor
00:04:26 --> 00:04:29 objects in low Earth orbit. 30 star
00:04:30 --> 00:04:32 trackers. That's an incredible network.
00:04:32 --> 00:04:35 And they're detecting approximately 30
00:04:35 --> 00:04:38 million transits daily across the fleet.
00:04:38 --> 00:04:40 That's a several order of magnitude
00:04:40 --> 00:04:42 increase in detection capability
00:04:42 --> 00:04:44 compared to conventional groundbased
00:04:44 --> 00:04:45 systems.
00:04:45 --> 00:04:46 >> The need for this kind of system has
00:04:46 --> 00:04:48 never been more urgent. Practices like
00:04:48 --> 00:04:51 leaving rocket bodies in LEO, operators
00:04:51 --> 00:04:53 maneuvering satellites without sharing
00:04:53 --> 00:04:55 trajectory predictions, and
00:04:55 --> 00:04:57 anti-satellite tests have all heightened
00:04:57 --> 00:04:59 collision risks. Conventional methods
00:04:59 --> 00:05:01 typically observe objects only a limited
00:05:01 --> 00:05:03 number of times per day, causing large
00:05:03 --> 00:05:05 uncertainties in orbital predictions.
00:05:05 --> 00:05:08 What makes Stargaze particularly
00:05:08 --> 00:05:10 powerful is that it provides conjunction
00:05:10 --> 00:05:12 screening results within minutes
00:05:12 --> 00:05:13 compared to the current industry
00:05:13 --> 00:05:16 standard of several hours. That speed
00:05:16 --> 00:05:18 can be the difference between a
00:05:18 --> 00:05:20 successful collision avoidance maneuver
00:05:20 --> 00:05:23 and a catastrophic impact.
00:05:23 --> 00:05:25 >> Basics actually shared a realworld
00:05:25 --> 00:05:27 example that demonstrates just how
00:05:27 --> 00:05:30 critical the system is. In late 2025, a
00:05:30 --> 00:05:32 Starlink satellite encountered a
00:05:32 --> 00:05:34 conjunction with a third party satellite
00:05:34 --> 00:05:36 that was performing maneuvers but whose
00:05:36 --> 00:05:39 operator wasn't sharing ephemeris data.
00:05:39 --> 00:05:41 >> Emerous data, that's the trajectory
00:05:41 --> 00:05:43 prediction information, right?
00:05:43 --> 00:05:45 >> Exactly. So, initially the close
00:05:45 --> 00:05:47 approach was anticipated to be about
00:05:47 --> 00:05:49 9 m away, considered a safe missed
00:05:50 --> 00:05:51 distance with zero probability of
00:05:51 --> 00:05:54 collision. But then, just 5 hours before
00:05:54 --> 00:05:56 the conjunction, the third party
00:05:56 --> 00:05:58 satellite performed a maneuver that
00:05:58 --> 00:05:59 collapsed the anticipated missed
00:06:00 --> 00:06:02 distance to just 60 m.
00:06:02 --> 00:06:06 >> 60 m. That's terrifyingly close in space
00:06:06 --> 00:06:08 terms. Stargaze quickly detected this
00:06:08 --> 00:06:10 maneuver and published an updated
00:06:10 --> 00:06:12 trajectory to the screening platform,
00:06:12 --> 00:06:14 generating new conjunction data messages
00:06:14 --> 00:06:17 that were immediately distributed. The
00:06:17 --> 00:06:19 Starling satellite was able to react
00:06:19 --> 00:06:20 within an hour of detecting the
00:06:20 --> 00:06:22 maneuver, planning an avoidance maneuver
00:06:22 --> 00:06:24 to reduce collision risk back down to
00:06:24 --> 00:06:25 zero.
00:06:25 --> 00:06:27 >> And here's the really important part.
00:06:27 --> 00:06:30 SpaceX is making this data available to
00:06:30 --> 00:06:33 all satellite operators free of charge.
00:06:33 --> 00:06:34 Starting this spring, satellite
00:06:34 --> 00:06:36 operators who submit their own
00:06:36 --> 00:06:38 trajectory predictions to the platform
00:06:38 --> 00:06:40 will receive conjunction data messages
00:06:40 --> 00:06:42 against Stargaze data.
00:06:42 --> 00:06:44 >> It's been in closed beta with over a
00:06:44 --> 00:06:46 dozen participating satellite operators
00:06:46 --> 00:06:48 and the response has been positive.
00:06:48 --> 00:06:50 SpaceX is drawing a parallel to
00:06:50 --> 00:06:52 commercial aviation. There are hundreds
00:06:52 --> 00:06:54 of thousands of sites daily, but they
00:06:54 --> 00:06:56 avoid collisions because they broadcast
00:06:56 --> 00:06:58 their location and flight plans to other
00:06:58 --> 00:07:01 aircraft. SpaceX is calling on all
00:07:01 --> 00:07:03 spacecraft operators to follow the same
00:07:03 --> 00:07:05 minimal standard of sharing predicted
00:07:05 --> 00:07:07 trajectories. Starlink updates and
00:07:08 --> 00:07:10 shares their ephemeris publicly every
00:07:10 --> 00:07:11 hour as an example.
00:07:11 --> 00:07:12 >> This is the kind of collaborative
00:07:12 --> 00:07:14 approach we need as space becomes more
00:07:14 --> 00:07:16 congested. It's not just about
00:07:16 --> 00:07:18 protecting SpaceX's massive
00:07:18 --> 00:07:20 constellation. It's about creating a
00:07:20 --> 00:07:22 safer orbital environment for everyone.
00:07:22 --> 00:07:25 Speaking of SpaceX, the company has
00:07:25 --> 00:07:27 temporarily grounded its Falcon 9 rocket
00:07:27 --> 00:07:29 following an issue with the upper stage
00:07:29 --> 00:07:31 on a recent Starlink launch, and the
00:07:31 --> 00:07:33 timing couldn't be more critical.
00:07:34 --> 00:07:36 >> This happened on Monday, February 2nd. A
00:07:36 --> 00:07:39 Falcon 9 successfully delivered 25
00:07:39 --> 00:07:41 Starlink satellites to low Earth orbit
00:07:41 --> 00:07:43 as planned. But after deploying the
00:07:43 --> 00:07:45 payloads, the rocket's upper stage
00:07:45 --> 00:07:47 failed to perform its de-orbit burn.
00:07:47 --> 00:07:49 That de-orbit burn is designed to bring
00:07:50 --> 00:07:51 the spent upper stage down for
00:07:51 --> 00:07:53 controlled destruction in Earth's
00:07:53 --> 00:07:56 atmosphere. Without it, we have another
00:07:56 --> 00:07:59 piece of debris in orbit. Exactly the
00:07:59 --> 00:08:00 kind of problem that Stargaze is
00:08:00 --> 00:08:02 designed to help monitor.
00:08:02 --> 00:08:04 >> The good news is the upper stage did
00:08:04 --> 00:08:07 manage to pacivate itself by venting
00:08:07 --> 00:08:09 propellant which lowered its perigee to
00:08:09 --> 00:08:12 about 110 km. According to satellite
00:08:12 --> 00:08:15 tracker Jonathan McDow, it will re-enter
00:08:15 --> 00:08:17 quickly. But SpaceX has grounded the
00:08:17 --> 00:08:19 Falcon 9 fleet while teams review data
00:08:20 --> 00:08:21 to determine root cause and corrective
00:08:21 --> 00:08:23 actions. And here's where the timing
00:08:23 --> 00:08:26 gets tricky. The Crew 12 astronaut
00:08:26 --> 00:08:27 mission to the International Space
00:08:28 --> 00:08:29 Station is currently scheduled to launch
00:08:29 --> 00:08:33 on February 11th, just 8 days from now.
00:08:33 --> 00:08:35 >> Crew 12 is particularly important
00:08:35 --> 00:08:37 because it will restore the ISS to its
00:08:37 --> 00:08:40 normal complement of seven crew members.
00:08:40 --> 00:08:42 The station has been operating with a
00:08:42 --> 00:08:44 skeleton crew of just three astronauts
00:08:44 --> 00:08:47 since January 15th when the four crew 11
00:08:47 --> 00:08:49 astronauts departed in the first ever
00:08:49 --> 00:08:52 medical evacuation from the ISS.
00:08:52 --> 00:08:54 >> NASA associate administrator Amit
00:08:54 --> 00:08:56 Kashatria confirmed that NASA teams from
00:08:56 --> 00:08:58 the commercial crew program are embedded
00:08:58 --> 00:09:00 in the investigation alongside SpaceX
00:09:00 --> 00:09:03 and the FAA. He said they're pressing
00:09:03 --> 00:09:05 towards the crew 12 window, but the
00:09:05 --> 00:09:06 launch will be contingent on the return
00:09:06 --> 00:09:09 to flight rationale. It's worth noting
00:09:09 --> 00:09:11 that the Falcon 9 has an incredible
00:09:11 --> 00:09:13 safety record. Last year alone, it
00:09:13 --> 00:09:15 launched a record-breaking
00:09:15 --> 00:09:18 165 times with all missions successful.
00:09:18 --> 00:09:20 Just a single mission experienced a
00:09:20 --> 00:09:23 significant anomaly, a Starlink launch
00:09:23 --> 00:09:25 where a booster toppled after landing at
00:09:25 --> 00:09:28 sea. That March 3rd incident was traced
00:09:28 --> 00:09:30 to a fuel leak in one of the booster
00:09:30 --> 00:09:32 nine Merlin engines which led to a fire
00:09:32 --> 00:09:35 that weakened a landing leg. SpaceX
00:09:35 --> 00:09:36 halted launches for a week at that time
00:09:36 --> 00:09:39 as well. The question now is whether
00:09:39 --> 00:09:40 they can resolve this upper stage issue
00:09:40 --> 00:09:43 quickly enough to meet the February 11th
00:09:43 --> 00:09:45 crew 12 launch date. If not, those three
00:09:45 --> 00:09:47 astronauts on the ISS will have to wait
00:09:47 --> 00:09:50 a bit longer for reinforcements. From
00:09:50 --> 00:09:52 orbital mechanics to the deepest reaches
00:09:52 --> 00:09:54 of space, the James Web Space Telescope
00:09:54 --> 00:09:57 has spotted something extraordinary. A
00:09:57 --> 00:09:59 fiveway galaxy merger in the early
00:09:59 --> 00:10:01 universe that's challenging our
00:10:01 --> 00:10:03 understanding of cosmic evolution.
00:10:03 --> 00:10:05 >> This is remarkable, Anna. The system
00:10:05 --> 00:10:08 consists of five compact, actively star
00:10:08 --> 00:10:10 forming galaxies that were emerging when
00:10:10 --> 00:10:12 the universe was only about 800 million
00:10:12 --> 00:10:15 years old. That's just 6% of the
00:10:15 --> 00:10:18 universe's current age. And the level of
00:10:18 --> 00:10:19 complexity is what's really stunning
00:10:20 --> 00:10:22 astronomers. These five galaxies are
00:10:22 --> 00:10:24 packed into a remarkably small region of
00:10:24 --> 00:10:26 space. They're separated by only tens of
00:10:26 --> 00:10:28 thousands of lightyear. To put that in
00:10:28 --> 00:10:30 perspective, that's far closer together
00:10:30 --> 00:10:32 than most neighboring galaxies in the
00:10:32 --> 00:10:33 modern universe.
00:10:33 --> 00:10:34 >> Dr.
00:10:34 --> 00:10:37 Hu from Texas&M University, the study's
00:10:37 --> 00:10:39 lead author, explained that what makes
00:10:39 --> 00:10:41 this remarkable is that a merger
00:10:41 --> 00:10:43 involving such a large number of
00:10:43 --> 00:10:45 galaxies was not expected so early in
00:10:45 --> 00:10:47 the universe's history. At that time,
00:10:47 --> 00:10:49 galaxy mergers were thought to be
00:10:49 --> 00:10:51 simpler, usually involving only two to
00:10:51 --> 00:10:52 three galaxies.
00:10:52 --> 00:10:54 >> But it's not just the number of galaxies
00:10:54 --> 00:10:56 that's impressive. These five galaxies
00:10:56 --> 00:10:59 are producing stars at a combined rate
00:10:59 --> 00:11:02 of roughly 250 solar masses per year.
00:11:02 --> 00:11:04 That's far exceeding typical star
00:11:04 --> 00:11:06 formation rates for that era.
00:11:06 --> 00:11:07 >> And this rapid stellar production has
00:11:08 --> 00:11:09 already enriched the system with heavier
00:11:09 --> 00:11:12 elements like oxygen. Materials forged
00:11:12 --> 00:11:14 in stellar interiors and dispersed
00:11:14 --> 00:11:16 through galactic interactions. The
00:11:16 --> 00:11:18 presence of these elements indicates
00:11:18 --> 00:11:20 that multiple generations of stars had
00:11:20 --> 00:11:22 already lived and died. The really
00:11:22 --> 00:11:24 fascinating part is that gas containing
00:11:24 --> 00:11:27 oxygen and hydrogen extends beyond the
00:11:27 --> 00:11:29 galaxies themselves. This suggests that
00:11:30 --> 00:11:31 gravitational interactions are pushing
00:11:32 --> 00:11:34 enriched material into intergalactic
00:11:34 --> 00:11:36 space, showing how early mergers may
00:11:36 --> 00:11:38 have shaped not just galaxies, but the
00:11:38 --> 00:11:41 larger cosmic environment. This
00:11:41 --> 00:11:42 discovery really disrupts the standard
00:11:42 --> 00:11:45 model of galaxy assembly. That model
00:11:45 --> 00:11:47 proposes a gradual buildup where small
00:11:47 --> 00:11:50 galaxies merge over long periods to form
00:11:50 --> 00:11:52 larger systems. But this fiveway merger
00:11:52 --> 00:11:55 demonstrates that complex multi-galaxy
00:11:55 --> 00:11:57 interactions were already underway less
00:11:57 --> 00:12:00 than a billion years after the Big Bang.
00:12:00 --> 00:12:02 >> Professor Casey Papovich, a co-author on
00:12:02 --> 00:12:05 the study, emphasized the implications
00:12:05 --> 00:12:08 by showing that a complex merger-driven
00:12:08 --> 00:12:11 system exists so early. It tells us our
00:12:11 --> 00:12:14 theories of how galaxies assemble and
00:12:14 --> 00:12:16 how quickly they do so need to be
00:12:16 --> 00:12:19 updated to match reality. This adds to
00:12:19 --> 00:12:22 the growing body of evidence from JWST
00:12:22 --> 00:12:24 that the early universe was capable of
00:12:24 --> 00:12:27 producing massive maturelook galaxies at
00:12:27 --> 00:12:29 astonishing speed. Matter in the early
00:12:29 --> 00:12:31 universe appears to have clustered more
00:12:31 --> 00:12:33 rapidly and efficiently than our
00:12:33 --> 00:12:35 simulation suggested.
00:12:35 --> 00:12:37 >> The study was published in Nature
00:12:37 --> 00:12:39 Astronomy and it's another example of
00:12:39 --> 00:12:43 how JWST is fundamentally changing our
00:12:43 --> 00:12:45 understanding of the cosmos.
00:12:45 --> 00:12:48 with cosmic mysteries, scientists have
00:12:48 --> 00:12:50 finally solved a 50-year-old puzzle
00:12:50 --> 00:12:52 about why nearby galaxies appear to be
00:12:52 --> 00:12:55 fleeing from our own Milky Way. And the
00:12:55 --> 00:12:57 answer involves a massive cosmic void
00:12:57 --> 00:12:59 right in our neighborhood.
00:12:59 --> 00:13:00 >> This is one of those mysteries that's
00:13:00 --> 00:13:03 been nagging at astronomers for decades,
00:13:03 --> 00:13:05 Avery. Most large galaxies near the
00:13:05 --> 00:13:07 Milky Way, with the exception of
00:13:07 --> 00:13:10 Andromeda, appear to be moving away from
00:13:10 --> 00:13:13 us and seem largely unaffected by the
00:13:13 --> 00:13:16 gravitational pole of our local group of
00:13:16 --> 00:13:17 galaxies.
00:13:17 --> 00:13:19 >> The local group being the Milky Way,
00:13:19 --> 00:13:21 Andromeda, and dozens of smaller
00:13:21 --> 00:13:24 galaxies. So, what's the solution? Led
00:13:24 --> 00:13:27 by Ewood at the Capta Institute in
00:13:27 --> 00:13:30 Granagan, an international research team
00:13:30 --> 00:13:32 used advanced computer simulations and
00:13:32 --> 00:13:35 discovered that matter just beyond the
00:13:35 --> 00:13:38 local group forms a broad flat structure
00:13:38 --> 00:13:40 stretching tens of millions of light
00:13:40 --> 00:13:44 years across. And here's the key. Vast
00:13:44 --> 00:13:46 empty regions lie above and below this
00:13:46 --> 00:13:47 structure.
00:13:48 --> 00:13:50 >> So we're basically living on a cosmic
00:13:50 --> 00:13:53 pancake surrounded by voids. That's
00:13:53 --> 00:13:55 actually a pretty good analogy. This
00:13:55 --> 00:13:58 flat distribution of matter is the only
00:13:58 --> 00:14:00 way to accurately account for both the
00:14:00 --> 00:14:02 combined mass of the Milky Way and
00:14:02 --> 00:14:05 Andromeda and the unexpected motions of
00:14:05 --> 00:14:07 nearby galaxies.
00:14:07 --> 00:14:09 >> But how does this flat structure explain
00:14:09 --> 00:14:12 why galaxies are moving away from us?
00:14:12 --> 00:14:15 >> It comes down to the local void, a vast
00:14:15 --> 00:14:18 empty region discovered back in 1987 by
00:14:18 --> 00:14:21 Brent Tully and Rick Fiser. The local
00:14:21 --> 00:14:25 void extends approximately 60 mega parex
00:14:25 --> 00:14:28 or about 200 million lightyear beginning
00:14:28 --> 00:14:30 at the edge of the local group. The
00:14:30 --> 00:14:32 local void is growing because there's
00:14:32 --> 00:14:34 very little matter inside it to exert
00:14:34 --> 00:14:37 gravitational pole. Our Milky Way sits
00:14:37 --> 00:14:39 in what's called the local sheet, a flat
00:14:39 --> 00:14:42 array of galaxies that bounds the void.
00:14:42 --> 00:14:44 And this local sheet is rushing away
00:14:44 --> 00:14:48 from the void center at 260 km/s.
00:14:48 --> 00:14:50 How fast is that affecting the Milky
00:14:50 --> 00:14:51 Way?
00:14:51 --> 00:14:53 >> The Milky Way's velocity away from the
00:14:53 --> 00:14:56 local void is 970
00:14:56 --> 00:15:01 km hour. That's 600 mph. It's
00:15:01 --> 00:15:03 astonishingly fast.
00:15:03 --> 00:15:05 >> So, the new simulations show that this
00:15:05 --> 00:15:08 hidden geometry, the flat plane of dark
00:15:08 --> 00:15:10 matter beyond the local group with voids
00:15:10 --> 00:15:13 above and below, is what's driving these
00:15:13 --> 00:15:15 galactic motions.
00:15:15 --> 00:15:17 >> Exactly. When researchers included this
00:15:17 --> 00:15:20 configuration in their simulations, they
00:15:20 --> 00:15:22 closely match the observed positions and
00:15:22 --> 00:15:25 speeds of nearby galaxies. It provides a
00:15:25 --> 00:15:27 coherent explanation for motions that
00:15:27 --> 00:15:29 have puzzled astronomers for half a
00:15:29 --> 00:15:30 century.
00:15:30 --> 00:15:32 >> This is connected to research about the
00:15:32 --> 00:15:34 Hubble tension, too, isn't it? The
00:15:34 --> 00:15:36 discrepancy in measurements of the
00:15:36 --> 00:15:38 universe's expansion rate.
00:15:38 --> 00:15:39 >> That's right. Some researchers have
00:15:39 --> 00:15:41 proposed that if we're inside a large
00:15:41 --> 00:15:44 local void, it could affect how we
00:15:44 --> 00:15:46 measure cosmic expansion, making the
00:15:46 --> 00:15:48 local universe appear to be expanding
00:15:48 --> 00:15:51 faster than it actually is. Though that
00:15:51 --> 00:15:53 particular idea remains controversial
00:15:53 --> 00:15:55 and needs more evidence. What's
00:15:55 --> 00:15:57 remarkable is that we're learning our
00:15:57 --> 00:15:59 immediate cosmic neighborhood is far
00:15:59 --> 00:16:01 more structured and dynamic than we
00:16:01 --> 00:16:03 previously understood. We're not just
00:16:04 --> 00:16:06 floating in a uniform sea of galaxies.
00:16:06 --> 00:16:09 We're on a sheet of matter bordering a
00:16:09 --> 00:16:10 massive void.
00:16:10 --> 00:16:13 >> And that void is shaping our galaxy's
00:16:13 --> 00:16:14 journey through space in fundamental
00:16:14 --> 00:16:15 ways.
00:16:15 --> 00:16:17 >> For our final story today, we're turning
00:16:17 --> 00:16:20 to some of the fastest objects in our
00:16:20 --> 00:16:23 galaxy. Runaway stars that are racing
00:16:23 --> 00:16:25 through the Milky Way at incredible
00:16:25 --> 00:16:27 speeds. Researchers from institutes
00:16:27 --> 00:16:29 across Spain have just completed the
00:16:29 --> 00:16:31 most extensive observational study to
00:16:31 --> 00:16:33 date of these stellar speeders,
00:16:34 --> 00:16:37 analyzing 2140 type stars, the brightest
00:16:37 --> 00:16:39 and most massive class of stars in our
00:16:39 --> 00:16:40 galaxy.
00:16:40 --> 00:16:42 >> These aren't just fastmoving stars,
00:16:42 --> 00:16:44 Avery. We're talking about stars with
00:16:44 --> 00:16:49 velocities that often exceed 700 km/s.
00:16:49 --> 00:16:51 That's fast enough to escape the Milky
00:16:51 --> 00:16:54 Way's gravity entirely. The term runaway
00:16:54 --> 00:16:56 stars was first used back in the early
00:16:56 --> 00:17:00 1960s by Dutch astronomer Adrien Blau.
00:17:00 --> 00:17:02 He observed stars moving at unusually
00:17:02 --> 00:17:04 high speeds and proposed they originated
00:17:04 --> 00:17:07 in binary systems and were ejected when
00:17:07 --> 00:17:09 the companion star collapsed and
00:17:09 --> 00:17:11 exploded in a supernova.
00:17:11 --> 00:17:14 >> By 2005, astronomers discovered even
00:17:14 --> 00:17:16 faster runaway stars, leading to the
00:17:16 --> 00:17:19 designation hypervelocity stars. These
00:17:19 --> 00:17:21 objects are fascinating because of the
00:17:21 --> 00:17:23 influence they have on galactic
00:17:23 --> 00:17:24 evolution.
00:17:24 --> 00:17:26 >> By escaping their systems of origin,
00:17:26 --> 00:17:28 these stars in radiate gas and dust in
00:17:28 --> 00:17:30 the interstellar medium, eventually
00:17:30 --> 00:17:32 seating it with heavy elements after
00:17:32 --> 00:17:35 they go supernova. This affects how
00:17:35 --> 00:17:37 future stars and planets will form.
00:17:37 --> 00:17:39 >> So, what did this new study reveal? The
00:17:39 --> 00:17:42 team used data from ESA's Gaia
00:17:42 --> 00:17:45 Observatory and the IAOB spectroscopic
00:17:45 --> 00:17:49 database to analyze these 2140 type
00:17:49 --> 00:17:51 stars. They found that most runaway
00:17:51 --> 00:17:54 stars rotate slowly while those that
00:17:54 --> 00:17:56 rotate faster are more likely to be
00:17:56 --> 00:17:57 linked to supernova explosions and
00:17:58 --> 00:18:00 binary systems. And here's an
00:18:00 --> 00:18:01 interesting finding. The highest
00:18:01 --> 00:18:03 velocity stars tend to be single,
00:18:03 --> 00:18:05 suggesting they were ejected from young
00:18:05 --> 00:18:07 clusters through gravitational
00:18:07 --> 00:18:10 interactions. So there are actually two
00:18:10 --> 00:18:11 different mechanisms creating runaway
00:18:12 --> 00:18:12 stars.
00:18:12 --> 00:18:15 >> Exactly. Some are explosively ejected by
00:18:15 --> 00:18:18 supernova in binary systems while others
00:18:18 --> 00:18:20 are gravitationally ejected from close
00:18:20 --> 00:18:23 encounters with star clusters. The study
00:18:23 --> 00:18:25 helps clarify the relative contributions
00:18:25 --> 00:18:28 of these two mechanisms. Lead author Mar
00:18:28 --> 00:18:30 Caretero Castrio, now at the European
00:18:30 --> 00:18:32 Southern Observatory, called this the
00:18:32 --> 00:18:34 most comprehensive observational study
00:18:34 --> 00:18:36 of its kind in the Milky Way. By
00:18:36 --> 00:18:38 combining information on rotation and
00:18:38 --> 00:18:40 binarity, they're providing
00:18:40 --> 00:18:42 unprecedented constraints on how these
00:18:42 --> 00:18:45 runaway stars are formed. The team also
00:18:45 --> 00:18:48 identified 12 runaway binary systems,
00:18:48 --> 00:18:50 including three X-ray binary sources
00:18:50 --> 00:18:52 that contain neutron stars or black
00:18:52 --> 00:18:54 holes and three additional systems that
00:18:54 --> 00:18:56 are likely candidates for hosting black
00:18:56 --> 00:18:59 holes. Perhaps the strongest evidence
00:18:59 --> 00:19:01 for multiple ejection mechanisms was
00:19:01 --> 00:19:04 this. Virtually no stars in the study
00:19:04 --> 00:19:06 exhibited both high velocities and rapid
00:19:06 --> 00:19:09 rotation. If all runaway stars came from
00:19:09 --> 00:19:11 the same process, you'd expect to see
00:19:11 --> 00:19:14 some with both characteristics. Future
00:19:14 --> 00:19:16 Gaia data releases and ongoing
00:19:16 --> 00:19:17 spectroscopic studies will help
00:19:17 --> 00:19:20 astronomers trace these stars back to
00:19:20 --> 00:19:22 their birthplaces within the Milky Way,
00:19:22 --> 00:19:24 which will confirm which mechanism was
00:19:24 --> 00:19:26 responsible in each case. And there
00:19:26 --> 00:19:28 might be another fascinating angle to
00:19:28 --> 00:19:30 this research. Understanding these
00:19:30 --> 00:19:32 systems could shed light on another role
00:19:32 --> 00:19:34 they may play in galactic evolution,
00:19:34 --> 00:19:36 potentially distributing the basic
00:19:36 --> 00:19:38 ingredients of life throughout the Milky
00:19:38 --> 00:19:40 Way as they travel. Cosmic messengers
00:19:40 --> 00:19:42 carrying the seeds of life across the
00:19:42 --> 00:19:44 galaxy. That's a beautiful thought to
00:19:44 --> 00:19:45 end on.
00:19:45 --> 00:19:47 >> And that wraps up today's episode of
00:19:47 --> 00:19:48 Astronomy Daily.
00:19:48 --> 00:19:50 >> From NASA's moon mission delays to
00:19:50 --> 00:19:53 SpaceX's new safety innovations, from
00:19:53 --> 00:19:55 ancient galaxy mergers to mysteries in
00:19:55 --> 00:19:57 our cosmic neighborhood, it's been quite
00:19:58 --> 00:19:59 a journey through the cosmos today.
00:19:59 --> 00:20:01 >> Thanks for joining us. For more space
00:20:01 --> 00:20:03 news, visit our website at
00:20:03 --> 00:20:05 astronomydaily.io, io where you can
00:20:05 --> 00:20:07 explore our full archive and stay
00:20:07 --> 00:20:08 updated on the latest cosmic
00:20:08 --> 00:20:09 discoveries.
00:20:09 --> 00:20:11 >> You can also find us on social media at
00:20:12 --> 00:20:14 Astro Daily Pod across all major
00:20:14 --> 00:20:16 platforms. Until next time, keep looking
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