Astronomy
Featured picks
- How Mars Built a Giant Volcanic Region Without Plate Tectonics
Mars lacks plate tectonics, so volcanoes kept erupting in one region for billions of years, piling up lava until the crust was heavily stressed and fractured.
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- The Star That Passed Closest to Our Solar System 70,000 Years Ago
About 70,000 years ago, Scholz's binary star system passed within 0.8 light-years of the Sun, likely crossing the outer Oort Cloud.
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- Titan Has Air Thick Enough to Skip a Pressurized Spacesuit
Titan has surface pressure about 1.5 times Earths, so a human would not need a pressurized suit there, but would still need oxygen and extreme cold protection.
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- Asteroid, Meteoroid, Meteor, Meteorite: What Is the Difference?
A space rock can be a meteoroid, meteor, or meteorite depending on where it is, while asteroids are larger rocky bodies orbiting the Sun.
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- The Black Hole Image That Needed Half a Ton of Hard Drives
The first black hole image used about 5 petabytes of data, filling over half a ton of hard drives, and some of it was faster to fly than send online.
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- Up to 85% of Stars May Belong to Multiple-Star Systems
Up to 85% of stars may belong to systems with two or more stars, making solitary stars like our Sun unusual by star count.
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- Up to Half of Earth’s Water May Be Older Than the Sun
Up to half of Earth’s water may have formed in interstellar space before the Sun and survived the birth of our solar system.
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- How Massive Stars Collapse Into Neutron Stars Only About 10 Kilometers Wide
Some massive stars swell into red giants, then explode and leave behind a neutron-star core only about 10 kilometers across.
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- Betelgeuse Will Eventually Explode as a Supernova Bright Enough to See by Day
Betelgeuse, a red supergiant in Orion, will eventually explode as a supernova bright enough to see by day for months, but it will not harm Earth.
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- Saturn Is the Solar System’s Only Planet Less Dense Than Water
Saturn is the only planet with an average density lower than water, so a gigantic enough water tank could theoretically let it float.
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- Earth’s Moon Is Exceptionally Large Compared With Its Planet
Earth’s Moon is the Solar System’s largest and heaviest moon relative to its planet, measuring about 27% of Earth’s width and 1.2% of its mass. [oai_citation:0‡NASA Space Science Data Archive](https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html?utm_source=chatgpt.com)
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- If the Solar System Fit in Your Hand, the Milky Way Would Span North America
Shrink the Solar System to fit in your palm, and the Milky Way would stretch across North America, with hundreds of billions of stars inside it.
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- The Sun Has Made Only About 20 Trips Around the Milky Way
The Sun takes about 230 million years to orbit the Milky Way, so in its roughly 4.6-billion-year life it has made only about 20 trips.
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- The Milky Way May Have Trillions of Rogue Planets
Scientists estimate the Milky Way may contain trillions of rogue planets drifting without a star, including many around Earth mass.
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- We Have Never Taken a Full Photo of the Milky Way From Outside
There is no real photo of the entire Milky Way from outside because Earth and our spacecraft are inside the galaxy; full views are built from observations and models.
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- Mercury Is Actually Earth’s Closest Planet on Average
Mercury is Earth’s closest planet on average, and it is also the closest planet to every other planet in the solar system.
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- Earth Is the Solar System’s Only Known Place With Ordinary Fire
Earth is the only known place in our solar system where ordinary fire occurs, and no known exoplanet has enough oxygen for it.
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- Why the Moon Can Almost Perfectly Cover the Sun
The Sun is about 400 times wider than the Moon but also about 400 times farther away, making total solar eclipses possible and revealing the Sun's faint outer atmosphere.
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- The First Confirmed Planets Beyond Our Solar System Were Found in 1992
We did not confirm planets beyond our solar system until 1992, when two were found orbiting a pulsar; the first around a Sun-like star came in 1995.
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- Why Smaller Black Holes Can Have Stronger Tidal Forces
Small black holes can have much stronger tidal forces at their event horizons, while supermassive black holes may let you cross the horizon without being torn apart.
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