Blue Comet Meets Blue Stars
12.02.2018

What's that heading for the Pleiades star cluster? It appears to be Comet C/2016 R2 (PanSTARRS), but here, appearances are deceiving. On the right and far in the background, the famous Pleiades star cluster is dominated by blue light from massive young stars.

APOD: 2025 November 25 Б Comet Lemmon and the Milky Way
25.11.2025

What did Comet Lemmon look like when it was at its best? One example is pictured here, featuring three celestial spectacles all at different distances. The closest spectacle is the snowcapped Meili Mountains, part of the Himalayas in China.

Periodic Comet Swift Tuttle
8.08.2024

A Halley-type comet with an orbital period of about 133 years, Comet 109P/Swift-Tuttle is recognized as the parent of the annual Perseid Meteor Shower. The comet's last visit to the inner Solar System was in 1992.

Comet Hale Bopp Over Val Parola Pass
28.06.1998

In 1997, Comet Hale-Bopp became much brighter than any surrounding stars. It could be seen even over bright city lights. Out away from city lights, however, it put on quite a spectacular show. Here Comet Hale-Bopp was photographed last March above Val Parola Pass in the Dolomite mountains surrounding Cortina d'Ampezzo, Italy.

NGC 4676: When Mice Collide
4.10.2021

These two mighty galaxies are pulling each other apart. Known as the "Mice" because they have such long tails, each spiral galaxy has likely already passed through the other. The long tails are created by the relative difference between gravitational pulls on the near and far parts of each galaxy.

NanoSail D2
2.01.2026

In 2011, on January 20, NASA's NanoSail-D2 unfurled a very thin and very reflective 10 square meter sail becoming the first solar sail spacecraft in low Earth orbit. Often considered the stuff...

Announcing Comet Machholz
13.12.2004

A comet discovered only this summer is brightening quickly and already visible to the unaided eye. Comet C/2004 Q2 (Machholz) is currently best visible in Earth's Southern Hemisphere where some observers report it brighter than magnitude 5. The comet is moving rapidly to northern skies and should continue to brighten until early January.

NGC 4676: When Mice Collide
26.04.2009

These two mighty galaxies are pulling each other apart. Known as "The Mice" because they have such long tails, each spiral galaxy has likely already passed through the other. They will probably collide again and again until they coalesce.

A Dust Jet from the Surface of Comet 67P
6.11.2017

Where do comet tails come from? There are no obvious places on the nuclei of comets from which the jets that create comet tails emanate. Last year, though, ESA's Rosetta spacecraft not only imaged a jet emerging from Comet 67P/Churyumov-Gerasimenko, but flew right through it.

APOD: 2023 November 26 Б A Dust Jet from the Surface of Comet 67P
26.11.2023

Where do comet tails come from? There are no obvious places on the nuclei of comets from which the jets that create comet tails emanate. In 2016, though, ESA's Rosetta spacecraft not only imaged a jet emerging from Comet 67P/Churyumov-Gerasimenko, but flew right through it.