Cosmology | Astronomy.com

Unveiling the Andromeda Galaxy’s true nature

Alison Klesman — Fri, 10 Oct 2025 15:00:00 +0000

Over the course of human history, perhaps no single object in the night sky has drawn more attention than the Andromeda Galaxy, which the 10th-century Persian astronomer Abd al-Rahman al-Sufi dubbed a “nebulous smear.” For centuries, the fuzzy object nestled in the night sky between her mythological parents, Cepheus and Cassiopeia, and winged Pegasus heldContinue reading "Unveiling the Andromeda Galaxy’s true nature"

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Are dark matter and dark energy only an illusion?

Michael E. Bakich — Thu, 09 Oct 2025 14:39:58 +0000

Ask most astronomers, and they’ll tell you that dark matter and dark energy make up more than 95 percent of the universe and that they are the explanations for many of the large-scale phenomena we observe. But a new study published Sept. 12 in the journal Galaxies offers a different scenario: that what we see is the weakeningContinue reading "Are dark matter and dark energy only an illusion?"

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How is the total mass of the universe calculated?

Astronomy Staff — Mon, 15 Sep 2025 13:00:00 +0000

How is the total mass of the universe calculated? Bob GiddingsGreen Bay, Wisconsin Calculating the total mass of the universe is not simple, because most of the mass is invisible. In a pie chart of the contents of the universe, only 5 percent is normal matter, atoms that make up all the planets, stars, andContinue reading "How is the total mass of the universe calculated?"

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Scientists seek to discover what came before the Big Bang

Brooks Mendenhall — Thu, 28 Aug 2025 14:54:52 +0000

A team of scientists claims a computational tool for studying black hole collisions could be our best bet for answering mysterious questions about the universe’s origins. In a new paper in Living Reviews in Relativity, they argue for applying a technique called numerical relativity to peer into the moment before the Big Bang. At itsContinue reading "Scientists seek to discover what came before the Big Bang"

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How did Edwin Hubble prove Andromeda was a galaxy?

Astronomy Staff — Mon, 07 Jul 2025 13:00:00 +0000

How did a Cepheid variable star help Edwin Hubble prove the Andromeda Nebula was a galaxy? Roger BradySan Quentin, California Cepheids are rare variable stars with periods ranging from about 1 to 120 days. Their light curve — a chart showing brightness over time — is characterized by rapid brightening followed by slow dimming inContinue reading "How did Edwin Hubble prove Andromeda was a galaxy?"

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Could AI help us better understand the universe?

Lakshmi Chandrasekaran — Sat, 28 Jun 2025 13:00:00 +0000

For almost as long as humans have existed, we have been trying to make sense of the cosmos. What started as philosophical musing has, following the advent of the telescope and the ability to look ever farther into space (and ever earlier in time), become a thriving field of research. Today, scientists seek to understandContinue reading "Could AI help us better understand the universe?"

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June 9, 1988: First image of an Einstein ring

Elisa Neckar — Mon, 09 Jun 2025 13:00:00 +0000

In early 1987, a team led by MIT’s Jacqueline Hewitt was imaging radio-emitting objects with the Very Large Array radio telescope as part of a gravitational lens survey. The unusual appearance of object MG1131+0456 – an oval with elongated bright spots at the ends – led to further investigation, and the researchers eventually concluded itContinue reading "June 9, 1988: First image of an Einstein ring"

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Astronomers have discovered the Big Wheel — here’s why it’s significant

Daniela Mata — Wed, 14 May 2025 17:13:13 +0000

Deep observations from the James Webb Space Telescope (JWST) have revealed an exceptionally large galaxy in the early universe. It’s a cosmic giant whose light has travelled over 12 billion years to reach us. We’ve dubbed it the Big Wheel, with our findings published March 17 in Nature Astronomy. This giant disk galaxy existed withinContinue reading "Astronomers have discovered the Big Wheel — here’s why it’s significant"

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Why some astronomers are starting to doubt cosmology’s standard model

Daniela Mata — Thu, 08 May 2025 01:27:32 +0000

A recent study published in The Astrophysical Journal Letters has provided the most precise distance to the Coma Cluster of galaxies yet — and also has deepened a crisis in cosmology. The problem is that when we look around the local universe, the universe seems to be expanding faster than predicted by the current modelsContinue reading "Why some astronomers are starting to doubt cosmology’s standard model"

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New findings suggest dark energy may be changing over time

Alison Klesman — Wed, 30 Apr 2025 14:00:00 +0000

Our universe has been expanding ever since it was born in the Big Bang. For decades, most cosmologists believed the universe’s expansion was slowing. Gravity, pulling on all matter, would eventually overcome the momentum from the Big Bang, halting or even reversing the expansion. But in 1998, supernova observations revealed a surprise: the universe isContinue reading "New findings suggest dark energy may be changing over time"

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