Lunar Eclipse Perspectives
5.02.2020

Do we all see the same Moon? Yes, but we all see it differently. One difference is the apparent location of the Moon against background stars -- an effect known as parallax. We humans use the parallax between our eyes to judge depth.

Historic Optical Flash Fades
22.04.1997

The largest telescopes in the world have scrambled to point toward this faint, fading object. Why? Because it may well be the first active optical counterpart ever found for a gamma-ray burst, and could hold the clue to the distance scale to this most enigmatic class of astronomical objects.

APOD: 2023 March 28 Á A Multiple Green Flash Sunset
28.03.2023

Yes, but can your green flash do this? A green flash at sunset is a rare event that many Sun watchers pride themselvesáon having seen.á Once thought to be a myth, a green flash is now understood to occur when the Earth's atmosphere acts like both a prism and a lens.

APOD: 2024 February 25 Á A Phoenix Aurora over Iceland
25.02.2024

All of the other aurora watchers had gone home. By 3:30 am in Iceland, on a quiet September night, much of that night's auroras had died down. Suddenly, unexpectedly, a new burst of particles streamed down from space, lighting up the Earth's atmosphere once again.

Hubble Telescope Maps Pluto
11.03.1996

No spacecraft from Earth has yet explored Pluto but astronomers have found ways of mapping its surface. A stunning map of this distant, diminutive planet, the first based on direct images, was revealed late last week in a Hubble Space Telescope press release.

The Magellanic Stream
15.08.2013

In an astronomical version of the search for the source of the Nile, astronomers now have strong evidence for the origin of the Magellanic Stream. This composite image shows the long ribbon...

Comet over California
7.03.2008

Still gracing northern skies, a fading Comet Holmes lies at the top edge of this colorful skyview, recorded on March 4. The reddish emission nebula below it is NGC 1499, also known as the California Nebula for its resemblance to the outline of the state on the US west coast.

APOD: 2011 December 11 Searching for Meteorites in Antarctica
11.12.2011

Where is the best place on Earth to find meteorites? Although meteors fall all over the world, they usually just sink to the bottom of an ocean, are buried by shifting terrain, or are easily confused with terrestrial rocks.

Rumors of a Strange Universe
2.03.1998

In a meeting in California two weeks ago, unpublished results were presented indicating that most of the energy in our universe is not in stars or galaxies but is tied to space itself. In the language of cosmologists, a large cosmological constant is directly implied by new distant supernovae observations.

Eta Carinae and the Expanding Homunculus Nebula
1.12.2014

How did the Eta Carinae star system create this unusual expanding nebula? No one knows for sure. About 170 years ago, the southern star system Eta Carinae (Eta Car) mysteriously became the second brightest star system in the night sky. Twenty years later, after ejecting more mass than our Sun, Eta Car unexpectedly faded.