Astronomy

It turns out that measuring the distance to a star is an interesting problem! Astronomers have come up with two different techniques to estimate how far away any given star is.

You know Saturn and Venus and Mars. Can you put the eight planets of the solar system in the correct order? There are several ways to do this.

ByValerie Stimac

Not sure what you're seeing in the night sky? Astronomy software such as Stellarium makes stargazing easier by helping to explain what you're seeing when you look at the stars.

ByValerie Stimac

Scientists have observed flashes of X-rays coming from behind a supermassive black hole, consistent with Albert Einstein's prediction that extremely large objects can bend light.

ByPatrick J. Kiger

The gegenschein, "faint light" in German, occurs under very specific astronomical conditions when the sun reaches the exact opposite of Earth from wherever you're stargazing.

ByValerie Stimac

The Mars solar conjunction occurs every two years and forces NASA to stop communicating with assets on the Red Planet. So what's the deal?

BySharise Cunningham

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.

ByPatrick 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.

ByValerie 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?

ByValerie Stimac&Desiree Bowie

A look at the night sky at any time of year will reveal a faint band of light stretching across the sky -- our solar system's home, the Milky Way. How much do we really know about it?

ByCraig Freudenrich, Ph.D.

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?

ByJonathan Strickland

月亮通常是天空中最大的物体或者tside of the sun. What is the moon made of, how did it form -- and why do people blame it for their strange behavior?

ByCraig 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.

ByJohn 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?

ByKatherine Neer&Yves Jeffcoat

Galaxies got their start nearly 14 billion years ago, with one unimaginably hot, dense and tiny pinpoint. How did we arrive at the universe's sprawling state of galactic affairs today?

ByRobert Lamb

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?

ByRobert 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?

ByRobert Lamb

如果我是在月球和地球是黑色的(没有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?

ByCraig 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.

ByCraig 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?

ByJulia Layton&Craig Freudenrich, Ph.D.

When you look up at night and see thousands of stars, have you ever wondered what you are looking at? Learn what stars are and how they live and die!

ByCraig Freudenrich, Ph.D.

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

ByPatrick 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?