Seven Worlds for TRAPPIST 1
23.02.2017

Seven worlds orbit the ultracool dwarf star TRAPPIST-1, a mere 40 light-years away. In May 2016 astronomers using the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) announced the discovery of three planets in the TRAPPIST-1 system.

Planets and Fire by Moonlight
9.07.2008

On July 5th, wandering planets, bright stars, and a young crescent Moon graced western skies after sunset. Arrayed along the solar system's ecliptic plane, the three celestial beacons forming this skyscape's eye-catching line-up with the Moon are Saturn (upper left), then Mars, and finally Regulus, alpha star of the constellation Leo.

Planetary Systems Now Forming in Orion
7.12.1996

How do planets form? Astronomers are finding out by studying one of the most interesting of all astronomical nebulae known, the Great Nebula in Orion. Insets to above mosaic show several planetary systems in formation. The bottom left insert shows the relative size of our own Solar System. The Orion Nebula contains many stellar nurseries.

A December Winter Night
28.12.2024

Orion seems to come up sideways, climbing over a distant mountain range in this deep skyscape. The wintry scene was captured from southern Poland on the northern hemisphere's long solstice night. Otherwise unseen nebulae hang in the sky, revealed by the camera modified to record red hydrogen-alpha light.

Mu Cephei
12.10.2023

Mu Cephei is a very large star. An M-class supergiant some 1500 times the size of the Sun, it is one of the largest stars visible to the unaided eye, and even one of the largest in the entire Galaxy.

Portrait of an Infant Solar System
7.06.2002

This infant solar system was discovered posing along the lonely outskirts of the Rho Ophiuchi dark cloud, a star forming region 500 light-years from Earth. Enlarged in this infrared false-color portrait from the European...

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.

Comet Leonard Before Star Cluster M3
12.12.2021

Comet Leonard is now visible to the unaided eye -- but just barely. Passing nearest to the Earth today, the comet is best seen this week soon after sunset, toward the west, low on the horizon.

Trees, Stars, Aurora
9.02.2012

Have you ever seen an aurora? Auroras are occurring again with increasing frequency. With the Sun being unusually dormant over the past four years, the amount of Sun-induced auroras has been unusually low. More recently, however, our Sun has become increasingly active and exhibiting a greater abundance of sunspots, flares, and coronal mass ejections.

Planets, Great Wall, and Solar Eclipse
18.07.2009

This dramatic skyscape was recorded during the August 2008 total solar eclipse. The Moon's silhouette surrounded by a glistening solar corona hangs above the Jiayuguan Fort along the western edge of the Great Wall of China.