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FAQs

What are the seasons like on Uranus?

Image via Lawrence Sromovsky / Keck Observatory.

Image via Lawrence Sromovsky / Keck Observatory.

Uranus, like Earth, has four seasons. But that’s where the similarity ends. For starters, each season on Uranus lasts 21 (Earth) years.

What are cloud streets?

NASA's Aqua satellite captured this image of cloud streets over the Black Sea on January 8, 2015.  NASA Earth Observatory image courtesy Jeff Schmaltz LANCE/EOSDIS MODIS Rapid Response Team, GSFC.

NASA’s Aqua satellite captured this image of cloud streets over the Black Sea on January 8, 2015. NASA Earth Observatory image courtesy Jeff Schmaltz LANCE/EOSDIS MODIS Rapid Response Team, GSFC.

Cloud streets are long rows of cumulus clouds that are oriented parallel to the direction of the wind. They’re formed by convection rolls of rising warm air and sinking cool air, and ultimately become oriented parallel to the direction of the wind. Check out some cool images of cloud streets, inside.

Why can’t we feel Earth’s spin?

Sky wheeling around Polaris, the North Star.

A time exposure of the northern sky, revealing the apparent motion of all the stars around Polaris. In fact, this apparent motion is due to Earth’s spin. Image via Shutterstock

Earth spins on its axis once in every 24-hour day. At Earth’s equator, the speed of Earth’s spin is about 1,000 miles per hour (1,600 kph). The day-night has carried you around in a grand circle under the stars every day of your life, and yet you don’t feel Earth spinning. Why not? It’s because you and everything else – including Earth’s oceans and atmosphere – are spinning along with the Earth at the same constant speed.

What is radiocarbon dating?

From across the galaxy and across the Universe, from stars (including our Sun), pulsars, black holes and more, space is flooded with high-energy particles known as cosmic rays.  Check out The Cosmic Story of Carbon-14 by Ethan Siegel.  Image via Simon Swordy (U. Chicago), NASA.

Cosmic rays bombard Earth’s atmosphere, creating the unstable isotope carbon-14. This isotope lets scientists learn the ages of once-living specimens from long ago. Image via Ethan Siegel, Simon Swordy, NASA.

Radiocarbon dating is a technique used by scientists to learn the ages of biological specimens – for example, wooden archaeological artifacts or ancient human remains – from the distant past. It can be used on objects as old as about 62,000 years. Follow the links inside to learn more about radiocarbon dating.

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.

Outer space is big. Really, really, really big. And that’s why NASA has no plans at present to send a spacecraft to any of the known planets beyond our solar system. Alpha Centauri is the nearest star system to our sun at 4.3 light-years away. Can’t we even go that far? The answer is … not easily. A distance of 4.3 light-years equals trillions of miles 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? Follow the links inside to learn more.

Why do stars seem brighter at this time of year?

On June, July and August evenings, we look toward the galaxy’s center as indicated by the red arrows. On December, January and February evenings, we look away from the center, as indicated by the blue arrows. Other features, including our galaxy’s primary spiral arms and the sun’s location in the Orion Spur, are also shown. Artist’s illustration via NASA/JPL/Caltech/R.Hurt. View larger.

As seen from the Northern Hemisphere, the stars seem brighter in winter. Here’s why …

When does the Age of Aquarius begin?

Leonardo da Vinci's famous Vitruvian Man, a drawing created circa 1487, with the 7 chakras or energy centers indicated.  Image via Wikimedia Commons

Leonardo da Vinci’s famous Vitruvian Man, a drawing created circa 1487, with the 7 chakras or energy centers indicated. Image via Wikimedia Commons

The Age of Aquarius is an astrological age, which shifts roughly every 2,150 years. It’s defined by the sun’s position at the time of the March, or vernal, equinox. The Age of Aquarius begins when the March equinox point moves out of the constellation Pisces and into the constellation Aquarius. But there’s no definitive answer as to when that will be. This post explores some of the possibilities.

When is the next supermoon?

What most call a Blue Moon isn't blue in color. It's only Blue in name. This great moon photo from EarthSky Facebook friend Rebecca Lacey in Cambridge, Idaho.

Moon photo is from Rebecca Lacey in Cambridge, Idaho.

According to the definition of supermoon coined by Richard Nolle 30 years ago, the year 2015 has a total of six supermoons. They are the new moons of January, February and March and the full moons of August, September and October. The September 28, 2015 full moon will be the closest supermoon of 2015. It’ll also undergo a total lunar eclipse! Follow the links inside to learn about the supermoons of 2015.

Are the December solstice and January perihelion related?

Earth and sun via ISS Expedition 13 / NASA.

Earth and sun via ISS Expedition 13 / NASA.

Earth comes closest to the sun (perihelion) tomorrow. Meanwhile, the December solstice took place on December 21. Are the December solstice and January perihelion related? No. It’s just a coincidence that they come so close together. Click inside to see when perihelion will fall at the March equinox.

Why does the new year begin on January 1?

Photo credit: Daniel Moile

The date of New Year’s Day seems so fundamental that it’s almost as though nature ordained it. But New Year’s Day is a civil event. Its date is not precisely fixed by a seasonal marker.