Mammatus Clouds Over Olympic Valley
20.02.2011

What's happened to these clouds? Normal cloud bottoms are flat because moist warm air that rises and cools will condense into water droplets at a very specific temperature, which usually corresponds to a very specific height. After water droplets form that air becomes an opaque cloud.

Saturn and ISS
9.07.2022

Soaring high in skies around planet Earth, bright planet Saturn was a star of June's morning planet parade. But very briefly on June 24 it posed with a bright object in low Earth orbit, the International Space Station.

Galaxy Cove Vista
7.05.2013

To see a vista like this takes patience, hiking, and a camera. Patience was needed in searching out just the right place and waiting for just the right time. A short hike was needed to reach this rugged perch above a secluded cove in Julia Pfeiffer Burns State Park in California, USA.

Sunspots and Solar Eclipse
25.10.2014

A New Moon joined giant sunspot group AR 2192 to dim the bright solar disk during Thursday's much anticipated partial solar eclipse. Visible from much of North America, the Moon's broad silhouette is captured in this extreme telephoto snapshot near eclipse maximum from Santa Cruz, California.

Leonids 1998: A Safe Meteor Storm
16.11.1998

You're in no danger. During the meteor storm occurring tonight and tomorrow, thousands of bits of ice and rock will likely rain onto the Earth. Few, if any, will hit the ground. Touted as potentially the most active meteor shower since 1966, the Leonids of 1998 will be tracked by observers the world over.

A Meteor Over the Anza Borrego Desert
11.08.1999

Meteors will be flashing across your skies over the next two nights. Specifically, the Perseid Meteor Shower should be at its best just before each morning's dawn. Observers at dark locations might see as much as a meteor a minute.

Quaoar: Large Asteroid in the Outer Solar System
9.10.2002

Asteroids almost as large as planets are still being discovered in our own Solar System. Recently an asteroid more than half the size of Pluto was found orbiting at a distance only a little further than the Solar System's most distant planet.

APOD: 2023 March 13 Б Rainbow Tree
13.03.2023

What lies at the end of a rainbow? Something different for everyone. For the photographer taking this picture, for example, one end of the rainbow ended at a tree. Others nearby, though, would likely see the rainbow end somewhere else. The reason is because a rainbow's position depends on the observer.

Lick Observatory Moonrise
12.12.2008

As viewed from a well chosen location at sunset, October's gorgeous Full Moon rose behind Mount Hamilton, east of San Jose, California. Captured in this lovely telescopic view, historic Lick Observatory is perched on the mountain's 4,200 foot summit, observatory and rising Moon momentarily sharing the warm color of filtered sunlight.

Mid Eclipse and Milky Way
27.05.2021

May's perigee Full Moon slid through Earth's shadow yesterday entertaining night skygazers in regions around the Pacific. Seen from western North America, it sinks toward the rugged Sierra Nevada mountain range in this time-lapse series of the total lunar eclipse.