We Might Be Able to Measure Dark Energy Through the Milky Way's Collision With Andromeda

By Brian Koberlein - August 17, 2023 01:34 PM UTC | Milky Way
The Milky Way and Andromeda are set to collide in a few billion years but are still over two million light-years apart. Cosmologically, this is right next door, but it could still be far enough to measure the effect of dark energy, which is pushing back on the galaxies coming together. According to a new study, the movement of the two galaxies towards each other could give an upper limit on the cosmological constant model of dark energy. Other merging pairs of galaxies could provide more data and help refine the measurements.
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New Horizons is So Far Away, it Can Measure the True Darkness of the Universe

By Brian Koberlein - August 16, 2023 02:29 PM UTC | Cosmology
NASA's New Horizons Spacecraft has completed its flybys of Pluto and Arrakoth and is now about 8 billion kilometers from Earth. Although astronomers are looking for another Kuiper Belt target, they can send it towards; the spacecraft is perfectly positioned to look at the Universe itself. At such a great distance, the spacecraft is beyond the dust that causes light pollution in the inner Solar System, darker than the darker skies on Earth. This unique vantage point will measure just how dark the Universe is.
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Storms on Saturn Can Have Impacts That Last for Hundreds of Years

By Brian Koberlein - August 14, 2023 04:06 PM UTC | Planetary Science
While Jupiter has the famous Great Red Spot cyclonic storm, the other giant planets have less turbulent-looking surfaces. But they do have mighty storms all their own. According to a new study, mega-storms on Saturn can flare up every 20-30 years and have long-lasting effects that persist for centuries. The astronomers looked at Saturn's radio emissions and mapped the ammonia gas distribution. They found that the storms churn up this gas and can be used to trace when storms happened in the past.
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Vera Rubin Will Find Many More Interstellar Objects

By Brian Koberlein - August 13, 2023 04:05 PM UTC | Missions
Astronomers have discovered two interstellar objects, Oumuamua and 2I/Borisov. When the Vera C Rubin Observatory comes online next year, it'll scan the entire southern sky every few nights, revealing thousands of comets and asteroids. Some fraction of these will be interstellar objects, passing briefly through the Solar System. It's estimated that Vera Rubin will discover dozens of interstellar objects, some of which might make the perfect targets for an interceptor mission.
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Giant Tidal Waves are Crashing Onto the Surface of an Enormous Star

By Brian Koberlein - August 12, 2023 01:39 PM UTC | Stars
Although the surface of a star seems quite different from the ocean, the underlying effect of gravity can create similar conditions. One type of star is known as a "heartbeat star," where a binary system interacts with one another, generating enormous stellar tides from their mutual gravity. In one extreme system, the gravitational effect is 200 times larger than any heartbeat star seen before. An enormous wave is generated across the star as its binary companion approaches. Like ocean waves, these waves break, crashing down onto the star's surface.
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Evidence for Modified Gravity Found in the Motions of Binary Stars

By Brian Koberlein - August 11, 2023 02:09 PM UTC | Physics
There are two leading explanations for dark matter, massive particles that don't interact with regular matter apart from gravity and a subtle difference in how gravity behaves at large distances. Astronomers have studied the interactions of over 20,000 binary stars with wide orbits cataloged in Gaia data. They found that orbital accelerations of the stars match the predictions made by modified Newtonian gravity and provide compelling evidence for the MOND hypothesis over the dark matter being a particle.
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Astronomers Search for Dark Matter Annihilation at the Center of the Earth

By Brian Koberlein - August 10, 2023 12:52 PM UTC | Physics
If dark matter is made of heavy particles, they could become captured by the gravitational field of massive objects like stars or planets. Constrained in a small area, these particles could crash into one another and annihilate with radiation. Astronomers have searched through 10 years of data captured by the IceCube Neutrino Observatory at the South Pole for any evidence of this dark matter annihilation. Although they didn't detect any evidence, the next generation IceCube Update will significantly improve the search.
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Could This Supermassive Black Hole Only Have Formed by Direct Collapse?

By Brian Koberlein - August 09, 2023 01:15 PM UTC | Black Holes
One of the outstanding mysteries in astronomy is how supermassive black holes gained so much mass so early in the Universe. The traditional theory is that stellar mass black holes merge, building up to supermassive levels. Another theory suggests that supermassive black holes might have collapsed directly out of enormous clouds of gas and dust. Astronomers using JWST and Chandra think they've discovered a black hole that's too massive, too early, and could only have formed from direct collapse.
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Some Metal Meteorites Have a Tiny Magnetic Field. But How?

By Brian Koberlein - August 06, 2023 01:00 PM UTC | Planetary Science
A portion of the metallic meteorites found on Earth have traces of magnetism. This is surprising since you need a larger world with an internal dynamo like the Earth. New research suggests that iron-heavy asteroids can collect into piles of rubble, with other space rocks forming a cold inner pile surrounded by a warmer liquid outer layer. As the core draws heat from the outer layer, it initiates convection and a small magnetic field that is detectable in the iron meteorites billions of years later.
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Do Technological Civilizations Depend on Atmospheric Oxygen?

By Brian Koberlein - August 05, 2023 12:54 PM UTC | Astrobiology
Our modern technological civilization wouldn't have been possible without open-air combustion, which can only happen when atmospheric oxygen levels reach at least 18%. A new study asks if this could be a bottleneck for developing other advanced civilizations. Without at least 18% oxygen, fires won't easily burn, so technologies like steam power and combustion engines wouldn't be possible. Earth has only reached that level of atmospheric composition in the last 500 million years.
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