Supermoon Spectacle, Interstellar Comet Insights, and Mars' Ozone Mystery Uncovered

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Avery: Welcome, listeners, to Astronomy Daily, the

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podcast that brings the cosmos down to Earth.

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I'm Avery.

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Anna: And I'm Anna. We have a fantastic

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show for you today, packed with news from our

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celestial neighborhood and the farthest

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reaches of the universe.

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Avery: That's right, we'll be looking up at the

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biggest supermoon of 2025,

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tracking an interstellar visitor as it zips

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past the sun and uncovering a strange

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atmospheric mystery on Mars.

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Anna: And to cap it all off, we'll be exploring a

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mind bending new the that asks, what if

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dark matter doesn't exist at all?

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Avery: It's going to be a, um, big one.

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Let's get started with a sight we can all

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look forward to in our own night sky.

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Anna: Indeed, after a year of seeing the Moon

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looking a bit smaller than usual, we're in

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for a treat next week.

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11:48pm Eastern Time on

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October 6, to be precise, which,

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if I've done my math correctly,

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corresponds to 3:48

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UTC on October 7th

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will see the biggest and brightest supermoon

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of 2025.

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Avery: I'm already marking my calendar. So for

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our listeners who might be new to this, what

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exactly makes a full moon a, uh,

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supermoon?

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Anna: It's all about the moon's orbit. It's not a

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perfect circle, it's an ellipse. So

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sometimes the Moon is at its farthest point

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from Earth, which we call apogee. And

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sometimes it's at its closest point, or

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perigee. A supermoon happens when a full

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moon coincides with its perigee.

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Avery: And that makes it look bigger and brighter in

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the sky. Right. I read it can appear up to

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14% larger and 30% brighter than a

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micro moon, which is when the full moon

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happens at apogee.

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Anna: Exactly. And we've just come through a period

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of micro moons, so the difference will be

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quite noticeable. This particular supermoon

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is also the Harvest Moon, which is the full

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moon closest to the autumnal equinox.

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Avery: The harvest Moon. That's the one that

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historically helped farmers bring in their

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crops. Because it rises so close to sunset,

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giving them extra light to work by, it often

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looks huge and orange on the horizon.

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Anna: That's the one. The orange color is due to

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the same effect that makes sunsets red. The

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light is passing through more of Earth's

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atmosphere. So next week we get a combination

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of things. The closest full moon of the year

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and the beautiful effect of the harvest moon,

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all making for a spectacular celestial event.

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Avery: From something we can see with our own eyes

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to something that requires a fleet of

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interplanetary spacecraft.

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Let's get an update on the interstellar comet

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3i Atlas.

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Anna: This is incredibly exciting.

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3i Atlas is only the third

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interstellar object we've ever detected

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passing through our solar system. The first

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was Oumuamua and The second was

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2i Borisov. These objects are

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cosmic messengers from other star systems.

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Avery: And the European Space Agency is pulling out

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all the stops to study this one. From now

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until early November, they're planning to use

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a trio of their spacecraft, the Mars

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Express and ExoMars Trace Gas Orbiter,

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which are both orbiting Mars, and the JUICE

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spacecraft, which is on its way to Jupiter.

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Anna: The reason this is such a unique opportunity

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is because of the comet's trajectory. As it

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makes its closest approach to the sun, it's

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going to heat up dramatically. This heating

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causes ices on its surface to sublimate,

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turn directly into gas, releasing dust

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and revealing the chemical composition of the

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comet's nucleus.

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Avery: So it's like unwrapping a gift from another

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star. And using three different spacecraft

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gives them a huge advantage, doesn't it?

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Anna: It certainly does. Each spacecraft has

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different instruments and will see the comet

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from a different vantage point. This

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triangulation allows scientists to build a

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much more complete 3D picture of the comet's

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activity and the mater its shedding. By

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studying the composition of this gas and

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dust, we can learn about the building blocks

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of planets in whatever distant star system

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this comet came from.

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Avery: It's a reminder of how interconnected the

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galaxy is. A piece of another solar system

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just passing through for a quick visit.

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Incredible.

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Anna: Absolutely.

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Now let's bring our focus a little closer to

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home, to our planetary neighborhood,

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Mars. Scientists have been puzzled

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by a mysterious surge in ozone

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that appears over its north pole during the

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winter.

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Avery: M ozone on Mars. I, uh, usually

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associate ozone with Earth's protective

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layer. Is it the same thing?

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Anna: It's the same molecule. Three

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oxygen atoms bonded together. But

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on Mars, its behavior is very different.

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Using the ExoMars Trace Gas Orbiter.

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The same one. Watching the comet,

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scientists noticed that ozone

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concentrations in the middle atmosphere

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spike during the winter inside the

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polar vortex.

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Avery: A, uh, polar vortex. We have those on

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Earth too. Basically a giant spinning cyclone

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of frigid air, right?

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Anna: Precisely. And on Mars, it

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gets incredibly cold inside this

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vortex, dropping below minus

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1, 130 degrees Celsius.

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This cold is the key to the mystery.

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Normally, water vapor in the atmosphere

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reacts with other chemicals to destroy

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ozone.

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Avery: But when it gets that cold, the water vapor

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freezes out, forming ice clouds.

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So with the water vapor gone, the.

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Anna: Ozone destroying chemical reactions Stop.

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And the ozone is allowed to build up to

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much higher concentrations than seen

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anywhere else on the planet.

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Avery: That's a clever piece of atmospheric

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detective work. What does this tell us about

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Mars?

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Anna: It gives us a new way to trace the

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circulation of gases in the Martian

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atmosphere. And more importantly,

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it helps us understand the history of water

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on Mars. By tracking where and

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when water vapor is present, we can build

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better models of Mars past climate and

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figure out where all its ancient water went.

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Avery: From a mystery on Mars to the biggest

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mystery in the entire cosmos. Ana, uh, we

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have to talk about this new theory that

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challenges the very existence of dark matter

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and dark energy.

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Anna: This is one of those ideas that could either

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be a dead end or completely

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revolutionized cosmology. The standard

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model of the universe called Lambda

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CDM tells us that about

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95% of the universe is made of

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two invisible components, dark

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matter and dark energy.

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Avery: Right. Dark matter provides the extra gravity

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needed to hold galaxies together. And dark

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energy is, ah, a force that's causing the

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universe's expansion to accelerate. We can't

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see them, but we infer their existence from

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their effects.

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Anna: Exactly. But physicist Rajendra

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Gupta, uh, from the University of Ottawa, has

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proposed a new model that gets rid of both.

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His idea is based on a combination of

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other theories, including one about tired

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light and another covariing

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coupling constants.

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Avery: Whoa, those are some heavy terms. Let's break

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that down. Covariing coupling

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constants. What does that mean?

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Anna: In simple terms? It means that the

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fundamental constants of nature, things like

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the strength of gravity or the

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electromagnetic force, might not actually

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be constant. They could be changing very,

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very slowly as the universe ages and

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expands.

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Avery: So if the strength of these forces changed

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over billions of years, how would that

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replace dark matter?

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Anna: Gupta's model suggests that these

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changing constants could create effects that

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we currently misinterpret as dark matter.

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For example, the way galaxies rotate

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much faster than they should, which is, uh, a

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key piece of evidence for Dark matter could

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be explained by these evolving physical

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laws instead of an unseen particle.

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The model also accounts for the accelerated

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expansion of the universe without needing

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dark energy.

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Avery: So we might not be living in a universe

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filled with mysterious dark stuff, but in a

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universe where the fundamental rules are

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slowly changing. That's a profound thought.

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Anna: It is. It's important to stress that

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this is still a very new and

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untested hypothesis. The vast

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majority of evidence still points towards the

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standard lambda CDM model. But

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it's a fascinating alternative that reminds

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us to keep questioning our assumptions.

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It shows that there are still huge

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fundamental questions about our universe left

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to answer.

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Avery: And that is a perfect place to wrap up for

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today.

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From a supermoon in our backyard to an

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interstellar comet, a Martian weather

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mystery, and a whole new way to think about

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the universe itself, it's been a.

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Anna: Whirlwind tour of the cosmos. Thank you so

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much for joining us on Astronomy Daily. If

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you'd like to see more details on these

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stories and more, please visit our

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website@astronomydaily.IO

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and check out our continually updated

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newsfeed. And while there, you may like to

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sign up for our free daily newsletter as

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well.

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Avery: Join us again tomorrow as we continue to

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explore the wonders of the universe. Clear

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skies, everyone. And remember to keep looking

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up, especially this week.