Why Are There Shooting Stars?

iStock / Chloe Effron
iStock / Chloe Effron

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Have you ever seen a flash of bright light streaking through the night sky? People around the world have different ways of explaining these so-called shooting stars. But shooting stars aren’t really stars at all!

Shooting stars are really meteors (MEE-tee-ors)—little chunks of rock and dust moving through space. As the Earth orbits (or circles) the Sun, it sometimes comes close to these meteors. Meteors passing at high speeds through the layer of gases surrounding Earth, called the atmosphere (AT-muss-feer), causes friction (FRICK-shun). Friction is when one thing rubs against the other. And friction makes meteors glow.

Friction causes heat. Rocks and dust get super hot as they fly super fast through the Earth's atmosphere. The heat makes them glow until they burn out. We call that glowing streak in the sky a shooting star. (Now you know those aren’t stars at all!) Meteors burn out during the day too, but those bright flashes show up very clearly in the dark. On a normal night, you might see a meteor about every 10 to 15 minutes if you pay close attention. During a meteor shower like the Perseid, which comes every summer, you might be able to see about 100 meteors an hour! 

Want to find out more? Take this Discovery Kids quiz to learn the difference between meteors, comets, and asteroids.


Friday’s Best Amazon Deals Include Digital Projectors, Ugly Christmas Sweaters, and Speakers

Amazon
Amazon
As a recurring feature, our team combs the web and shares some amazing Amazon deals we’ve turned up. Here’s what caught our eye today, December 4. Mental Floss has affiliate relationships with certain retailers, including Amazon, and may receive a small percentage of any sale. But we only get commission on items you buy and don’t return, so we’re only happy if you’re happy. Good luck deal hunting!

3D Map Shows the Milky Way Galaxy in Unprecedented Detail

ESA
ESA

It's our galactic home, but the Milky Way contains many mysteries scientists are working to unravel. Now, as The Guardian reports, astronomers at the European Space Agency have built a 3D map that provides the most detailed look at our galaxy yet.

The data displayed in the graphic below has been seven years in the making. In 2013, the ESA launched its Gaia observatory from Kourou in French Guiana. Since then, two high-powered telescopes aboard the spacecraft have been sweeping the skies, recording the locations, movements, and changes in brightness of more than a billion stars in the Milky Way and beyond.

Using Gaia's findings, astronomers put together a 3D map that allows scientists to study the galaxy in greater depth than ever before. The data has made it possible to measure the acceleration of the solar system. By comparing the solar system's movement to that of more remote celestial objects, researchers have determined that the solar system is slowly falling toward the center of the galaxy at an acceleration of 7 millimeters per second per year, The Guardian reports. Additionally, the map reveals how matter is distributed throughout the Milky Way. With this information, scientists should be able to get an estimate of the galaxy's mass.

Gaia's observations may also hold clues to the Milky Way's past and future. The data holds remnants of the 10-billion-year-old disc that made up the edge of the star system. By comparing it to the shape of the Milky Way today, astronomers have determined that the disc will continue to expand as new stars are created.

The Gaia observatory was launched with the mission of gathering an updated star census. The previous census was conducted in 1957, and Gaia's new data reaches four times farther and accounts for 100 times more stars.

[h/t The Guardian]