APOD: 2023 December 11 Б Solar Minimum versus Solar Maximum
11.12.2023

The surface of our Sun is constantly changing. Some years it is quiet, showing relatively few sunspots and active regions. Other years it is churning, showing many sunspots and throwing frequent Coronal Mass Ejections (CMEs) and flares.

APOD: 2026 July 17 Б The Dust Trail of Comet Tempel 2
17.07.2026

Comet 10P/Tempel 2 orbits the Sun once every 5.4 years. Currently visible in binoculars or small telescopes toward the constellation Capricornus, the periodic comet is captured in this sharp telescopic image from July 11 sporting a bright nuclear region and pretty greenish coma.

Moon Games
1.08.2008

The Moon's measured diameter is around 3,476 kilometers (2,160 miles). But apparent angular size, or the angle covered by an object, can also be important to Moon enthusiasts. Angular size depends on distance, the farther away an object is, the smaller an angle it covers.

Video: Comet Leonard over One Hour
25.01.2022

Which direction is this comet heading? Judging by the tail, one might imagine that Comet Leonard is traveling towards the bottom right, but a full 3D analysis shows it traveling almost directly away from the camera.

Anticrepuscular Rays Over Wyoming
21.02.2012

What's happening over the horizon? Although the scene may appear somehow supernatural, nothing more unusual is occurring than a setting Sun and some well placed clouds. Pictured above are anticrepuscular rays. To understand them, start by picturing common crepuscular rays that are seen any time that sunlight pours though scattered clouds.

The View from Stereo Ahead
22.12.2006

On December 22nd, at 0022 Universal Time the Sun reached its southernmost point in Earth's sky marking the final season change for the year 2006. In celebration of the Solstice, consider these images of the Sun from an extreme ultraviolet telescope onboard the Stereo Ahead spacecraft.

Flare Well AR2673
14.09.2017

Almost out of view from our fair planet, rotating around the Sun's western edge giant active region AR2673 lashed out with another intense solar flare followed by a large coronal mass ejection on September 10.

Sunrise Analemma (with a little extra)
20.09.2012

An analemma is that figure-8 curve that you get when you mark the position of the Sun at the same time each day throughout planet Earth's year. In this case, 17 individual images...

APOD: 2024 November 6 Б Comet Tsuchinshan Atlas over the Dolomites
6.11.2024

Comet Tsuchinshan-Atlas is now headed back to the outer Solar System. The massive dusty snowball put on quite a show during its trip near the Sun, resulting in many impressive pictures from planet Earth during October. The featured image was taken in mid-October and shows a defining visual feature of the comet -- its impressive anti-tail.

APOD: 2025 November 3 Б A Double Helix Lunar Eclipse
3.11.2025

The image was timed to capture a total lunar eclipse -- but it came with quite a twist. First, the eclipse: the fully Earth-shadowed Moon is visible as the orange orb near the top.