Leonid Meteors Streak
23.11.2004

The 2004 Leonids meteor shower had its ups and downs. Although average rates were significantly less than many previous years, as expected, at least two unexpected "mini-outbursts" of several bright meteors over a few minutes were reported.

Sun 360: STEREO Captures Views of the Entire Sun
7.02.2011

For the first time, the entire Sun is being imaged all at once. This has become possible because the two STEREO satellites orbiting and monitoring the Sun are now on opposite sides of the Sun.

APOD: 2023 June 18 Б Saturns Northern Hexagon
18.06.2023

Why would clouds form a hexagon on Saturn? Nobody is sure. Originally discovered during the Voyager flybys of Saturn in the 1980s, nobody has ever seen anything like it anywhere else in the Solar System.

APOD: 2023 July 3 Б Venus in Ultraviolet from Akatsuki
3.07.2023

Why is Venus so different from Earth? To help find out, Japan launched the robotic Akatsuki spacecraft which entered orbit around Venus late in 2015 after an unplanned five-year adventure around the inner Solar System.

The W in Cassiopeia
18.03.2016

A familiar, zigzag, W pattern in northern constellation Cassiopeia is traced by five bright stars in this colorful and broad mosaic. Stretching about 15 degrees across rich starfields, the celestial scene includes dark clouds, bright nebulae, and star clusters along the Milky Way. In yellow-orange hues Cassiopeia's alpha star Shedar is a standout though.

Julius Caesar and Leap Days
29.02.2020

In 46 BC Julius Caesar reformed the calendar system. Based on advice by astronomer Sosigenes of Alexandria, the Julian calendar included one leap day every four years to account for the fact that an Earth year is slightly more than 365 days long.

Phi Persei: Double Star
2.10.1999

It's clear who is the biggest star in this binary system. Based on recent results, this artist's vision of the double star Phi Persei, 720 light years away, shows a bright, rapidly rotating massive star surrounded by a disk of gas. A small companion star orbits 100 million miles away.

STARFORGE: A Star Formation Simulation
23.06.2021

How do stars form? Most form in giant molecular clouds located in the central disk of a galaxy. The process is started, influenced, and limited by the stellar winds, jets, high energy starlight, and supernova explosions of previously existing stars.

A Twisted Meteor Trail Over Tenerife
2.06.2010

Did this meteor take a twisting path? No one is sure. Considered opinions are solicited. Meteors, usually sand sized grains that originate in comets, will typically disintegrate as they enter the Earth's atmosphere. A fast moving meteor ionizes molecules in the Earth's atmosphere that subsequently glow when they reacquire electrons.

Lewins Challenge: 360 Degree Star Trails
17.07.2011

You could be the first person ever to take a real single-exposure image like this. The above image from Vienna, Austria is not real in the sense that the 360 degree star trails in the sky appear only because of a digital trick.