A Telescope Laser Creates an Artificial Star
7.02.2005

What do you get when you combine one of the world's most powerful telescopes with a powerful laser? An artificial star. Monitoring fluctuations in brightness of a genuine bright star can indicate how the Earth's atmosphere is changing, but many times no bright star exists in the direction where atmospheric information is needed.

Summer at the South Pole
23.12.2000

The December solstice brings the beginning of Winter to Earth's Northern Hemisphere and Summer time to the South! This view of Earth's Southern Hemisphere near the beginning of Summer was created using images from the Galileo spacecraft taken during its December 1990 flyby of our fair planet.

A Partial Solar Eclipse over Buenos Aires
20.02.2018

What's happened to top of the Sun? Last week, parts of Earth's southern hemisphere were treated to a partial solar eclipse, where the Moon blocks out part of the Sun. The featured image was taken toward the end of the eclipse from the coast of Uruguay overlooking Argentina's Buenos Aires.

The Da Vinci Glow
3.04.2025

A 26 hour old Moon poses behind the craggy outline of the Italian Dolomites in this twilight mountain and skyscape. The one second long exposure was captured near moonset on March 30. And while...

Large Sunspot Group AR 9393
11.04.2001

The largest sunspot group of the past ten years crossed the surface of the Sun late last month and early this month. The group was designated Active Region 9393 as it was the 9393rd region identified since counting officially began in 1973.

Crescent Neptune and Triton
18.06.2006

Gliding silently through the outer Solar System, the Voyager 2 spacecraft camera captured Neptune and Triton together in crescent phase in 1989. The above picture of the gas giant planet and its cloudy moon was taken from behind just after closest approach.

Degas Ray Crater on Mercury
16.12.2000

Like the Earth's Moon, Mercury is scarred with craters testifying to an intense bombardment during the early history of the Solar System. In 1974, the Mariner 10 spacecraft surveyed this innermost planet up close, producing the only detailed images of its tortured surface.

CMBR Dipole: Speeding Through the Universe
8.10.2006

Our Earth is not at rest. The Earth moves around the Sun. The Sun orbits the center of the Milky Way Galaxy. The Milky Way Galaxy orbits in the Local Group of Galaxies. The Local Group falls toward the Virgo Cluster of Galaxies.

APOD: 2024 July 1 Б Time Spiral
1.07.2024

What's happened since the universe started? The time spiral shown here features a few notable highlights. At the spiral's center is the Big Bang, the place where time, as we know it, began about 13.8 billion years ago.

Red Sprite Lightning
11.11.1995

Recently two new types of lightning have been verified: red sprites and blue jets. These atmospheric discharges occur very high in the Earth's atmosphere - much higher than the familiar form of lightning.