Does the Milky Way Have Too Many Satellite Galaxies?

Large Magellanic Cloud. Credit: ESA

The Large and Small Magellanic Clouds are well known satellite galaxies of the Milky Way but there are more. It is surrounded by at least 61 within 1.4 million light years (for context the Andromeda Galaxy is 2.5 million light years away) but there are likely to be more. A team of astronomers have been hunting for more companions using the Subaru telescope and so far, have searched just 3% of the sky. To everyone’s surprise they have found nine previously undiscovered satellite galaxies, far more than expected. 

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Astronomers are on the Hunt for Dyson Spheres

Artist's impression of a Dyson Sphere. The construction of such a massive engineering structure would create a technosignature that could be detected by humanity. Credit: SentientDevelopments.com/Eburacum45
Artist's impression of a Dyson Sphere. The construction of such a massive engineering structure would create a technosignature that could be detected by humanity. Credit: SentientDevelopments.com/Eburacum45

There’s something poetic about humanity’s attempt to detect other civilizations somewhere in the Milky Way’s expanse. There’s also something futile about it. But we’re not going to stop. There’s little doubt about that.

One group of scientists thinks that we may already have detected technosignatures from a technological civilization’s Dyson Spheres, but the detection is hidden in our vast troves of astronomical data.

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One in Twelve Stars Ate a Planet

When a star eats a planet, it changes the star's metallicity. New research based on co-natal stars shows that one in twelve stars have eaten at least one planet. Image Credit: International Gemini Observatory/NOIRLab/NSF/AURA/M. Garlick/M. Zamani

That stars can eat planets is axiomatic. If a small enough planet gets too close to a large enough star, the planet loses. Its fate is sealed.

New research examines how many stars eat planets. Their conclusion? One in twelve stars has consumed at least one planet.

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This New Map of 1.3 Million Quasars Is A Powerful Tool

This figure from the research shows the sky distribution of the new Quaia quasar catalogue in Galactic coordinates and is displayed using a Mollweide projection. The grey region across the center is the Milky Way, a blind spot in the Quaia catalogue. Image Credit: K. Storey-Fisher et al. 2024

Quasars are the brightest objects in the Universe. The most powerful ones are thousands of times more luminous than entire galaxies. They’re the visible part of a supermassive black hole (SMBH) at the center of a galaxy. The intense light comes from gas drawn toward the black hole, emitting light across several wavelengths as it heats up.

But quasars are more than just bright ancient objects. They have something important to show us about the dark matter.

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Nancy Grace Roman will Map the Far Side of the Milky Way

Spiral galaxy seen in visible and infrared

The Galaxy is a collection of stars, planets, gas clouds and to the dismay of astronomers, dust clouds. The dust blocks starlight from penetrating so it’s very difficult to learn about the far side of the Galaxy. Thankfully the upcoming Nancy Grace Roman telescope has infrared capability so it can see through the dust. A systematic survey of the far side of the Milky Way is planned to see what’s there and could discover billions of objects in just a month. 

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Are Andromeda and the Milky Way Already Exchanging Stars?

Artist's illustration of Andromeda/Milky Way Merger. Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger

I often drag out the amazing fact that the Andromeda Galaxy, that faint fuzzy blob just off the corner of the Square of Pegasus, is heading straight for us! Of course I continue to tell people it won’t happen for a few billion years yet but a recent study suggests that we are already seeing hypervelocity stars that have been ejected from Andromeda already. It is just possible that the two galaxies have already started to exchange stars long before they are expected to merge. 

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Astronomers Build a 3D Map of Dust Within Thousands of Light-Years

3D Map of Dust in Galaxy

If you explore the night sky it won’t be long before you realise there is a lot of dust and gas up there. The interstellar dust between the stars accounts for 1% of the mass of the interstellar medium but reflects 30% of the starlight in infrared wavelengths. The dust plays a key role in the formation of stars and the evolution of the Galaxy. A team of astronomers have attempted to map the dust out to a distance of 3000 light years and have just released the first 3D map of the dust in our Galaxy. 

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Scientists Track How a Giant Wave Moved Through Our Galactic Backyard

Illustration: Radcliffe Wave model
This illustration shows how the Radcliffe Wave moves through the backyard of our sun (shown as a yellow dot). The white line represents the wave's current shape and motion. Magenta and green lines show how the wave is expected to move over time. (Credit: Ralf Konietzka, Alyssa Goodman and WorldWide Telescope via CfA)

Astronomers say there’s a wave rippling through our galactic neighborhood that’s playing a part in the birth and death of stars — and perhaps in Earth’s history as well.

The cosmic ripple, known as the Radcliffe Wave, was identified in astronomical data four years ago — but in a follow-up study published today by the journal Nature, a research team lays out fresh evidence that the wave is actually waving, like the wave that fans in a sports stadium create by taking turns standing up and sitting down.

“Similar to how fans in a stadium are being pulled back to their seats by the Earth’s gravity, the Radcliffe Wave oscillates due to the gravity of the Milky Way,” study lead author Ralf Konietzka, a researcher at Harvard and the Harvard-Smithsonian Center for Astrophysics, or CfA, said in a news release

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The SETI Ellipse Tells Us Where to Search for Extraterrestrial Civilizations

The SETI Ellipsoid (Image credit: Zayna Sheikh)

Of all the questions that remain unanswered, the question of life in the Universe is surely the one that captures our attention the most. In a Universe whose observable edge is 46 billion light years away, is it even conceivable that we are alone, the sole planet among the millions and perhaps billions that are out there, where life has evolved, an oasis of life in the cosmic ocean. In the search for alien civilisations, researchers have proposed that it may be possible to use bright galactic events like supernovae to act as a focal point for civilisations to announce their presence! 

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Astronomers Measure the Mass of the Milky Way by Calculating How Hard it is to Escape

Artist view of the Milky Way galaxy. Credit: ESA

If you want to determine your mass, it’s pretty easy. Just step on a scale and look at the number it gives you. That number tells you the gravitational pull of Earth upon you, so if you feel the number is too high, take comfort that Earth just finds you more attractive than others. The same scale could also be used to measure the mass of Earth. If you place a kilogram mass on the scale, the weight it gives is also the weight of Earth in the gravitational field of the kilogram. With a bit of mass, you have the mass of Earth.

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