Instead of pulling galaxies in our universe together, gravity seems to be driving them apart. How can gravity be repulsive, when our everyday experience shows it’s attractive? That’s why we need dark energy …
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.
Sharks are incredibly unlikely to bite you. They’re even less likely to kill you. However, we remain fascinated with their ability – and occasional proclivity – to do just that.
That glow over the unlit part of a crescent moon – called earthshine – is light reflected from Earth.
Beautiful photos in this post!
The word for it is “petrichor.” It’s the name of an oil that’s released from Earth into the air before rain begins to fall.
When a missile or meteor strikes the earth, the havoc above ground is obvious, but the details of what happens below ground are harder to see. Duke University physicists have developed techniques that enable them to simulate high-speed impacts in artificial soil and sand in the lab, and then watch what happens underground close-up, in super slow motion.
Glories are common. They seen all the time by people traveling in airplanes. You need the sun to be directly behind your head. In front, you need an ordinary cloud. As you look toward the cloud, look for the shadow of the airplane. The plane’s shadow may be surrounded by a multi-colored circle of light. That’s the glory.
There are a couple of theories that suggest what creates the strange greenish-yellow color that can precede a storm.
During a lunar eclipse, you’ll see the Earth’s shadow creeping across the moon’s face. The shadow will appear dark, like a bite taken out of the moon’s face, until the shadow completely covers the moon. Then, during the breathtaking moments of totality, the shadow on the moon’s face often often suddenly changes. Instead of dark, it appears red. Why?
It’s sometimes said that, on a worldwide scale, solar eclipses outnumber lunar eclipses by about a three to two margin. True?