The Solar System

Early dark energy, a form of dark energy that may have existed a few hundred thousand years after the big bang, could help clarify the universe's rate of expansion. But its existence hasn't been proven.

By Patrick J. Kiger

Astronomers at Haleakalā Observatory in Hawaii noted a bright X-ray emission in 2018, which persisted for three weeks and glowed ten times more brightly than previously studied supernovas, but are just now beginning to understand it.

By Valerie Stimac

In recent years, Saturn has overtaken Jupiter as the planet with the most moons in our solar system. How many does it have and could it have even more?

By Valerie Stimac & Desiree Bowie

The changing phases of the moon have given us an enduring curiosity about the dark side of the moon. But is there really a dark side of the moon? What would we see there?

By Jonathan Strickland

The moon is often the largest object in the sky outside of the sun. What is the moon made of, how did it form -- and why do people blame it for their strange behavior?

By Craig Freudenrich, Ph.D.

Asteroid belts aren't quite the dense fields of gigantic spinning rocks that you may have seen in a "Star Wars" film, but they're still fascinating. In fact, the main asteroid belt may tell us how our entire solar system came into existence.

By John Fuller

You've probably heard that staring at the sun is bad — even a few seconds can damage your eyes. But what if you looked at a solar eclipse?

By Katherine Neer & Yves Jeffcoat

It's tough to wrap your mind around a time when the Earth wasn't here. So how do Earth and the rest of the planets out there get their start in the universe?

By Robert Lamb

We can't defy the odds of an asteroid taking a turn for Earth forever, so the world's astronomers watch the sky. What happens once they spot something?

By Robert Lamb

If I was on the moon and the earth was black (no lights were on) and a flashlight was turned on facing the moon, would I see the light? If I couldn't, would there be any way to detect any residual matter that came from the light on Earth or does light die after a certain distance?

Since the 1960s, we've been captivated by the planet Mars. How different is our neighbor, and what have we learned about the most explored planet?

By Craig Freudenrich, Ph.D., Nicholas Gerbis & Mark Mancini

A total solar eclipse is a rare event that can be an amazing thing to witness. Learn about solar eclipses and how to observe one safely.

By Craig Freudenrich, Ph.D.

Where I live it is pretty common to see "shooting stars" -- streaks of light in the sky at night. How big is a shooting star? Do they land on earth or do they burn up? Do they land on the ground as meteorites?

The sun warms our planet every day, provides the light by which we see and is necessary for life on Earth. But what is it exactly, and what will happen when it burns itself out?

By Julia Layton & Craig Freudenrich, Ph.D.

Pluto is relatively round and orbits the Sun. So, why doesn't it qualify as a planet?

By Patrick J. Kiger & Kathryn Whitbourne

If "nature abhors a vacuum," then why doesn't the vacuum of space suck away all of the Earth's atmosphere?

Can the curvature of the Earth only be seen from outer space? If you didn't know that the Earth is a sphere, there are three common observations you could use to convince yourself that it is.

The Chandler wobble is the change in the spin of Earth on its axis. Think of the wobble you see in a toy top when it first starts spinning or slows down. Its 'poles' do not spin in a perfectly straight line.

After Viking 1 captured images of what looked like a face on Mars, the public began to speculate. Had Martians carved a colossus, or was there another answer?

By Stephanie Watson

Although other planets have rings, none are as spectacular as Saturn's. What makes the planet's stratified rings, and how did they get there in the first place?

By Stephanie Watson

The only thing that's lurking in the shadows during a lunar eclipse is the moon. When Earth's shadow blocks sunlight from directly illuminating a full moon, you're witnessing a lunar eclipse.

By Jessika Toothman

Until recently, most people assumed that if Mars had liquid water, it no longer did and hadn't for quite some time. But scientists have recently noticed some anomalies in photos of Mars that may suggest there is water. Could there be life, too?

By Sarah Dowdey & Robert Lamb

As the search for Planet Nine wears on, and astronomers have yet to get so much as a glimpse of it, researchers are pondering what else the object might be.

By Ian O'Neill, Ph.D.

The Geminid meteor shower is one of the year's stronger displays in terms of number and size of meteors. When's the best time to see it?

By Christopher Hassiotis

The moon has seen a lot in its 4.5 million years of life, and this detailed geologic map serves as testament.

By Jesslyn Shields & Yara Simón