Planetary Nebula Mz3: The Ant Nebula
1.05.2005

Why isn't this ant a big sphere? Planetary nebula Mz3 is being cast off by a star similar to our Sun that is, surely, round. Why then would the gas that is streaming away create an ant-shaped nebula that is distinctly not round?

Comet Encke s Tail Ripped off
3.10.2007

Swinging inside the orbit of Mercury, on April 20th periodic comet Encke encountered a blast from the Sun in the form of a Coronal Mass Ejection (CME). When CMEs, enormous clouds of energetic particles ejected from the Sun, slam into Earth's magnetosphere, they often trigger auroral displays.

Spicules: Jets on the Sun
2.11.2010

Imagine a pipe as wide as a state and as long as the Earth. Now imagine that this pipe is filled with hot gas moving 50,000 kilometers per hour. Further imagine that this pipe is not made of metal but a transparent magnetic field.

Orion over Green Bank
23.02.2022

What will the huge Green Bank Telescope discover tonight? Pictured, the Robert C. Byrd Green Bank Telescope (GBT) on the lower right is the largest fully-pointable single-dish radio telescope in the world. With...

Filaprom on the Western Limb
24.06.2022

A solar filament is an enormous stream of incandescent plasma suspended above the active surface of the Sun by looping magnetic fields. Seen against the solar disk it looks dark only because it's a little cooler, and so slightly dimmer, than the solar photosphere.

APOD: 2024 April 2 Б Detailed View of a Solar Eclipse Corona
2.04.2024

Only in the fleeting darkness of a total solar eclipse is the light of the solar corona easily visible. Normally overwhelmed by the bright solar disk, the expansive corona, the sun's outer atmosphere, is an alluring sight.

The Radio Sky: Tuned to 408MHz
20.10.2001

Tune your radio telescope to 408MHz (408 million cycles per second) and check out the Radio Sky! You should find that frequency on your dial somewhere between US broadcast television channels 13 and 14.

The Tail of a Christmas Comet
25.12.2021

The tail of a comet streams across this three degree wide telescopic field of view captured under dark Namibian skies on December 21. In outburst only a few days ago and just reaching naked eye visibility Comet Leonard (C/2021 A1) is this year's brightest comet.

APOD: 2023 April 25 Б Northern Lights over Southern Europe
25.04.2023

Did you see an aurora over the past two nights? Many people who don't live in Earth's far north did. Reports of aurora came in not only from northern locales in the USA as Alaska, but as far south as Texas and Arizona. A huge auroral oval extended over Europe and Asia, too.

Sunspot Metamorphosis: From Bottom to Top
16.02.2005

Sunspots -- magnets the size of the Earth -- are normally seen flat on the Sun. The above digital metamorphosis, however, shows a sunspot as it appears at increasing heights, effectively in three dimensions. The above...