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Clouds that look like ocean waves

Photo credit: Paul Chartier

Photo credit: Paul Chartier

Here’s a special kind of cloud known to scientists as a Kelvin Helmholtz cloud. They look like breaking ocean waves, with the rolling eddies seen at the top of the cloud layers usually evenly spaced and easily identifiable.

Top 4 questions about tornadoes

Don't try this at home: Researchers study tornadoes from a safe distance.  Image via Josh Wurman, CSWR

Don’t try this at home: Researchers study tornadoes from a safe distance. Image via Josh Wurman, CSWR

May is the peak month for twisters here in the U.S. Here are a few things you might like to know …

Mars is bright! Here’s why

Earth will between between the sun and Mars on May 22, 2016.  Then, the distance between our two worlds will be at its least for this two-year period, and Mars will appear brightest in our sky.  Image via Fourmilab.

Earth will pass between between the sun and Mars on May 22, 2016. Then, the distance between our two worlds will be at its least for this two-year period, and Mars will appear brightest in our sky. Image via Fourmilab.

We’re beginning to get questions about that red “star” in the east each evening. It’s Mars! We’ll pass between Mars and the sun this weekend.

What is the sun’s proper name?

This is our sun.  It spins on its axis once in about 25 days.  Image via NASA

Our sun. By any other name, it’d still be awesome. Image via NASA 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 in the English language. Most of us just call it the sun.

Top 3 tips to avoid mosquito bites

Photo credit: João Trindade

Photo credit: João Trindade

Simple things you can do to get fewer mosquito bites this summer.

How long would it take to get to Alpha Centauri?

Credit: Mark Rademaker/Mike Okuda/Harold White/NASA.

What a spaceship with warp drive might look like. Credit: Mark Rademaker/Mike Okuda/Harold White/NASA.

Alpha Centauri is the nearest star system to our sun at 4.3 light-years away. That’s about 25 trillion miles (40 trillion km) away from Earth – nearly 300,000 times the distance from the Earth to the sun. How might we travel to Alpha Centauri, the next-nearest star? And how long would it take to get there? Read about star travel via conventional propulsion, warp drives, and more.

What makes a red rainbow?

Frances Pelletier caught this double red rainbow - and the planet Venus - on February 9, 2016 from Myrtle Beach, South Carolina.

Frances Pelletier caught this double red rainbow on February 9, 2016 from Myrtle Beach, South Carolina.

Red rainbows happen when the sun is on the horizon. They’re created in much the same process that causes a sunset or sunrise to look red. Details – and more photos – inside.

What are star trails? How can I capture them?

Montauk Point lighthouse. Photo: Neeti Kumthekar

Montauk Point lighthouse. Photo: Neeti Kumthekar

What are star trails? They are the continuous paths created by stars, produced during long time exposure photographs, as shown on this page. In other words, the camera doesn’t track along with the stars’ apparent motion as night passes (actually caused by Earth’s spin under the sky). Instead, the camera stays fixed, while, as the hours pass, the stars move. The resulting photos show the nightly movement of stars on the sky’s dome.

Why is Earth Day on April 22?

In the late 1960s, there were love-ins, be-ins ... and, like the first Earth Day, teach-ins.  Here are two organizers of the first Earth Day in 1970.  Image via earthday2013funphotos.com

In the late 1960s, there were love-ins, be-ins … and, like the first Earth Day, teach-ins. Here are two organizers of the first Earth Day in 1970. Image via earthday2013funphotos.com

April 22, 1970 – Arbor Day – was the first Earth Day. Today, a common practice in celebration of Earth Day is still to plant new trees.

What gives rainbows their curved shape?

View larger. | Photo taken January 10, 2016 by Jennifer Khordi.

Photo taken January 10, 2016 by Jennifer Khordi.

A rainbow isn’t a flat two-dimensional image on the dome of sky. It’s light along a three-dimensional cone, with your eyes at the tip.