Counting Stars, Tumbling Asteroids, and China's Space Breakthroughs

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Anna: Welcome to Astronomy Daily, your regular dose

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of the latest happenings in space and

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astronomy news. I'm Anna.

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Avery: And I'm Avery. We've got a fantastic lineup

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for you today. Diving into everything from

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the sheer number of stars in our galaxy to

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tumbling asteroids, exciting updates from

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China's space program, and even the detection

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of a truly enigmatic dark object.

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Anna: It's going to be a stellar episode. Pun

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intended.

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Let's kick things off with a question that's

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probably. Probably crossed everyone's mind.

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Just how many stars are there in the Milky

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Way?

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Avery: That's a great question, Anna. Uh, and the

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answer is more than you can imagine.

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Astronomers generally estimate around 100

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billion stars in our galaxy. But it's a

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number that really depends on a lot of

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different factors.

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Anna: 100 billion. Wow. And I imagine it's

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incredibly difficult to count them from our

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vantage point inside the galaxy. Right. All

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that dust gets in the way.

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Avery: Exactly. It's like trying to count trees from

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inside a dense forest. So astronomers

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often look to other galaxies, which are

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easier to observe as a whole, to develop

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their estimation methods.

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Anna: One primary method involves studying the

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luminosity of galaxies. Astronomers can

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estimate the total light output of a galaxy.

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And by understanding the typical luminosity

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of different star types, they can infer the

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total number of stars. This is often combined

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with observations of a galaxy's mass inferred

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from its rotation speed or the motion of its

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stars, as more massive galaxies generally

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contain more stars. Another approach

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involves analyzing the stellar populations

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within representative regions of a galaxy,

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then extrapolating those findings to the

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galaxy's full extent. While these methods

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provide robust estimates, the numbers are

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always subject to refinement as our

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observational capabilities improve and our

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understanding of stellar evolution and

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galactic structures deepens. So the

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exact number is always evolving, but our

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estimates become more precise over time.

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Avery: Moving on from the grand scale of galaxies,

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let's zoom in to something a bit closer to

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home. Asteroids. There's

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fascinating new research about why some

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asteroids spin smoothly and others

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tumble chaotically.

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Anna: Yes, this study is really shedding light on

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their past. It suggests an asteroid's

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rotation is largely determined by how

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frequently it's impacted by other space

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rocks. Which is quite an intuitive idea when

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you think about it.

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Avery: Absolutely. And it combines data from ESA's

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GAIA mission Advanced Modeling and AI

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spearheaded by Dr. Wen Honju from the

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University of Tokyo. It's a great example of

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interdisciplinary science, revealing the

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physics of asteroid rotation and even. Even

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their internal structure.

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Anna: Uh, what's particularly interesting is the

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interplay of two forces, collisions,

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which cause the tumbling and internal

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friction which tends to stabilize them into a

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regular spin. This creates a sort of natural

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boundary in asteroid populations.

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Avery: That's a fascinating dynamic. So it's a

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constant battle between disruptive forces and

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stabilizing ones. What does this natural

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boundary look like in terms of asteroid size

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or composition? Smaller

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asteroids, though easily tumbled by impacts,

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tend to restabilize relatively quickly due to

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their internal friction. It's like they have

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a built in dampener for chaotic motion.

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Anna: So the larger ones essentially shrug off most

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minor collisions, maintaining their steady

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spin. It takes a significant hit to disrupt a

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truly massive asteroid. It's essentially

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a size dependent threshold. For a small

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asteroid, even a relatively minor impact can

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induce tumbling. But its internal structure

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quickly absorbs that energy, Allowing it to

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settle back into a predictable spin. For

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larger asteroids, their sheer mass and

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gravitational integrity mean only a very

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substantial energetic collision. Would impart

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enough angular momentum to truly destabilize

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their rotation for an extended period. And

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crucially, this study also confirms the YORP

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effect. That's the YORP effect as

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a primary driver for rapid rotation in

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smaller asteroids. It highlights how

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radiation pressure can subtly reshape and

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spin up these smaller bodies. Something less

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influential on their larger, more massive

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counterparts. And in case you're wondering

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because I was and looked it up, YORP stands

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for Yarkovsky, OKeefe, Radzievsky Paddock.

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Honoring four scientists who contributed to

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the understanding of these radiation driven

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rotational changes in small bodies.

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Avery: Thank you. I was going to ask, but that's

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a good point about the YORP effect. Could you

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elaborate a little more on how that radiation

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pressure actually, actually works to spin up

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these asteroids? It sounds quite subtle.

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Anna: Essentially, as sunlight hits an asteroid, it

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absorbs some of the energy and then re emits

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it as heat. This re emitted heat carries a

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tiny bit of momentum. If the asteroid has an

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irregular shape or if its surface properties

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vary, it will re emit heat unevenly.

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This uneven re emission creates a very small

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continuous torque or twisting force. That can

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gradually increase or decrease the asteroid's

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speed spin rate over long periods. It's a

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subtle but powerful effect, Especially for

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smaller bodies where their mass is not enough

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to resist this gentle push.

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Avery: Speaking of important research, let's pivot

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to some exciting news from China's space

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program. It's truly a dynamic time

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with an accelerating launch cadence. And

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commercial providers on the verge of their

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maiden orbital flights.

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Anna: That's fascinating. What's the latest from

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the Tiangong Space Station?

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Avery: Tiangong has been incredibly busy.

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They recently completed their fourth

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spacewalk, A significant milestone

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they're also preparing for the Shenzhou 21

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mission, which will bring new taikonauts to

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the station, continuing long duration

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scientific experiments. Switching gears

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to deep space. New images have just

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arrived from Tianwen 2. The probe is on

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its way to the Near Earth asteroid Kamo

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Oalewa, aiming for a sample return,

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which would be a monumental achievement.

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And on the commercial front, the competition

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is heating up. We're seeing rapid progress in

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launch vehicles and engine testing.

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Landspace's powerful BF20 engine is

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undergoing advanced tests. And Deep Blue

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Aerospace's Lightning RS is also making

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strides. Galactic Energy's Palace 1

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is CAS Space's Lijian 2 and

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Orient Space's Yin Li 2 are all nearing their

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inaugural flights, promising to significantly

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boost China's access to space.

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Anna: That's incredible. What about China's crewed

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lunar mission plans?

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Avery: The Changcheng 10 rocket, crucial for

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China's ambitious crewed lunar missions,

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recently completed a successful tethered

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ignition test. This is a critical step,

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demonstrating its propulsion system's

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readiness for human spaceflight and

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future lunar landings. It really shows

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their long term vision and commitment to deep

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space exploration. So, as you can see, we

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may not hear a lot from the Chinese space

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program, but they are making rapid strides

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and are far from being idle.

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Anna: From ambitious missions to something far more

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elusive, astronomers have recently detected

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a, uh, mysterious dark object, not by its

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light, but purely by its gravitational pull.

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This is truly a groundbreaking discovery.

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Avery: That's right, Ana. The leading candidates are

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indeed a rogue black hole or neutron

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star, which are both remnants of massive

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stars. However, a less massive

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possibility is an isolated brown dwarf,

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a failed star that never quite ignited

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fusion. The key here is free floating,

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meaning it's not gravitationally bound to any

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star moving independently through the galaxy.

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Anna: That's a fascinating concept, free floating.

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So this object is truly isolated, not

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orbiting anything. And that's what makes it

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so challenging to detect without

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gravitational lensing. And this

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detection method, known as microlensing, is

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truly revolutionary. It works by observing

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how the dark object's gravity warps the light

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from a background star. As the object passes

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in front of the star, it temporarily

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brightens the background star's light, acting

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like a cosmic magnifying glass. This

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technique is incredibly sensitive to objects

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that emit no light of their own.

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Avery: This discovery is really pushing the

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boundaries of what we can detect. It provides

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crucial insights into the population of dark

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compact objects in our galaxy. Objects that

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don't emit light, but whose gravitational

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influence is undeniable. It also

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helps us refine our models of galactic

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structure and, and even gives us clues about

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the elusive nature of dark matter, especially

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if these objects turn out to be primordial

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black holes.

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Anna: And that wraps up another fascinating journey

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through the cosmos on Astronomy Daily. We've

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covered a lot of ground today, from the

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incredible dynamics of asteroids to

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groundbreaking Chinese space missions and the

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mysteries of dark objects.

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Avery: And, um, thank you for joining us on

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Astronomy Daily. For more space and

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astronomy news, be sure to visit our

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website@astronomydaily.IO

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and check out our continually updating news

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feed. Be sure to tune in again tomorrow for

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more captivating stories from beyond our

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world. Until then, keep looking up.