Hubble Floats Free
5.03.1997

Why put observatories in space? Most telescopes are on the ground. On the ground, you can deploy a heavier telescope and upgrade it more easily. The trouble is that Earth-bound telescopes must look through the Earth's atmosphere.

Proxima Centauri: The Closest Star
15.07.2002

What is the closest star to our Sun? It is Proxima Centauri, the nearest member of the Alpha Centauri triple star system. Light takes only 4.22 years to reach us from Proxima Centauri. This...

Astro 1 In Orbit
4.05.1996

In December of 1990, the Space Shuttle Columbia carried an array of astronomical telescopes high above the Earth's obscuring atmosphere to observe the Universe at ultraviolet and x-ray wavelengths. The telescopes, known...

Attack of the Laser Guide Stars
17.05.2018

Dodging powerful laser beams, a drone captured this stunning aerial view. The confrontation took place above the 8.2 meter diameter Very Large Telescopes of the Paranal Observatory on planet Earth. Firing during a test...

M1: The Crab Nebula from NOT
20.09.2005

This is the mess that is left when a star explodes. The Crab Nebula, the result of a supernova seen in 1054 AD, is filled with mysterious filaments. The filaments are not only tremendously...

Hawaii
15.12.1995

Aloha! With the graceful arc of the Earth's limb in the background, the entire Hawaiian Island archipelago is visible in this stunning photo taken by the astronauts onboard the shuttle Discovery in October of 1988. Along with popular beaches and tropical resorts, these volcanic islands offer extreme elevations with dark, dry, cloudless skies.

The Milky Way in Infrared
29.01.2000

At night, from a dark location, part of the clear sky looks milky. This unusual swath of dim light is generally visible during any month and from any location. Until the invention of the telescope, nobody really knew what the "Milky Way" was.

Infrared Uranus
20.10.1998

The Sun's third largest planet usually looks quite dull. Uranus typically appears as a featureless small spot in a small telescope or a featureless large orb in a large telescope. Last August, however...

APOD: 2026 March 10 Б Sky Glows over Paranal Observatory
9.03.2026

Are lasers from giant telescopes being used to defend the Earth? No. Lasers shot from telescopes are now commonly used to help increase the accuracy of astronomical observations. In some directions, Earth atmosphere-induced fluctuations in starlight can indicate how the air mass over a telescope is changing, but in other directions, no bright star exists.

APOD: 2023 September 13 Б NGC 4632: Galaxy with a Hidden Polar Ring
12.09.2023

Galaxy NGC 4632 hides a secret from optical telescopes. It is surrounded by a ring of cool hydrogen gas orbiting at 90 degrees to its spiral disk. Such polar ring galaxies have previously been discovered using starlight. However, NGC 4632 is among the first in which a radio telescope survey revealed a polar ring.