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FAQs

How much do oceans add to world’s oxygen?

Phytoplankton - the foundation of the oceanic food chain. image via NOAA

Phytoplankton – the foundation of the oceanic food chain. Scientists estimate that phytoplankton contribute between 50 to 85 percent of the oxygen in Earth’s atmosphere. Image via NOAA

Scientists agree that there’s oxygen from ocean plants in every breath we take. Most of this oxygen comes from tiny ocean plants – called phytoplankton – that live near the water’s surface and drift with the currents. Like all plants, they photosynthesize – that is, they use sunlight and carbon dioxide to make food. A byproduct of photosynthesis is oxygen. Scientists estimate that phytoplankton contribute between 50 to 85 percent of the oxygen in Earth’s atmosphere.

Why is Mars sometimes bright and sometimes faint?

Here is the view from above the solar system in early June 2014.  Earth passed between Mars and the sun in April, and now we are flying ahead of it in the race of the planets.  That's why Mars is fainter now than it was in April 2014.

Here is the view from above the solar system in early June 2014. At the center of these diagrams is the sun (yellow dot). Earth (third orbit) passed between Mars (fourth orbit) and the sun in April 2014. By June, we are flying ahead of it in the race of the planets. That’s why Mars is fainter now than it was in April 2014. Image via Fourmilab.

Mars is the world orbiting the sun one step outward from Earth’s orbit. Earth takes one year to orbit the sun once. Mars takes about two years. The orbits of Earth and Mars are the reason Mars is one of the most fascinating planets to watch in our sky, and they are the reason Mars is sometimes bright and sometimes faint. On April 8, 2014, Earth went between the sun and Mars. That’s why Mars was so bright this past April.

Now Mars is fainter, but it still lovely to behold, and its near the moon on the night of June 6.

The brightness of Mars in our sky depends on where our two planets are in orbit around the sun. Sometimes Earth is close to Mars, and sometimes we are far away.

We are relatively close – and Mars appears at its brightest in our sky for that two-year period – every time Earth passes between the sun and Mars. That’s what’s happening today.

How do hurricanes get their names?

hurricane-isabel-nasa-500

Astronaut Ed Lu captured this view of Hurricane Isabel in 2003 from the International Space Station. Image via Mike Trenchard, NASA.

Ever wonder how hurricanes get their names? And why do hurricanes have names at all? Meteorologists long ago learned that naming tropical storms and hurricanes helps people remember the storms, communicate about them more effectively, and so stay safer if and when a particular storm strikes a coast. Find out more about hurricane names inside.

What’s the birthstone for June?

Photo credit: Valentyn Volkov/Shutterstock

Photo credit: Valentyn Volkov/Shutterstock

Happy birthday to all our June baby friends! Your month has three traditional birthstones – pearl, moonstone, and alexandrite. Pearls, according to South Asian mythology, were dewdrops from heaven that fell into the sea. They were caught by shellfish under the first rays of the rising sun, during a period of full moon. In India, warriors encrusted their swords with pearls to symbolize the tears and sorrow that a sword brings. More ….

Does the North Star ever move?

Sky wheeling around Polaris, the North Star.

Sky wheeling around Polaris, the North Star.

Polaris – the North Star – is like the hub of a wheel. It doesn’t rise or set – instead, it appears to stay put in the northern sky.

What is earthshine?

The moon and Venus over  North Carolina by Ken Christison.

The moon and Venus over North Carolina by Ken Christison.

If you’ve been looking at the moon shortly before sunrise, you might have noticed not only the bright crescent of the moon, but also the rest of the moon as a dark disc. That pale glow on the unlit part of a crescent moon is light reflected from Earth. It’s called “earthshine.”

Which spiral arm of the Milky Way contains our sun?

Our sun is located between two major spiral arms of the Milky Way galaxy, in what is sometimes called the Orion Arm or Orion Spur. Image updated in 2010 by R. Hurt via Wikimedia Commons.

We live in an island of stars called the Milky Way, and many know that our Milky Way is a spiral galaxy. In fact, it’s a barred spiral galaxy. But where within this vast spiral structure do our sun and its planets – our solar system – reside? In fact, astronomers say, we’re not located in one of the Milky Way’s primary spiral arms. Instead, we’re located between the Sagittarius and Perseus Arms of the Milky Way. Our local spiral arm is sometimes Orion Arm, or sometimes the Orion Spur.

Why do stars twinkle?

If you could see stars and planets from outer space, both would shine steadily. But – from Earth – stars twinkle while planets shine steadily. Hank Green of SciShow explains in the video above, and you can read more inside.

What is the electromagnetic spectrum?

Color spectrum via Shutterstock

Color spectrum via Shutterstock


When you think of light, you probably think of what your eyes can see. But the light to which our eyes are sensitive is just the beginning; it is a sliver of the total amount of light that surrounds us. The electromagnetic spectrum is the term used by scientists to describe the entire range of light that exists. From radio waves to gamma rays, most of the light in the universe is, in fact, invisible to us!

What is the sun’s proper name?

Our sun.  By any other name, it'd still be awesome.  Image via NASA.

Our sun. By any other name, it’d still be awesome. Image via NASA.

You’ve no doubt heard some star names such as Polaris the North Star – or Betelgeuse in the constellation Orion. But, although it’s also a star, our sun doesn’t have a generally accepted and unique proper name. It’s just the sun.

Earth and other planets in our solar system have their own names. Does the sun have a name?