Earth Rotating Under Very Large Telescopes
1.06.2011

Why is the Earth moving in the above video? Most time lapse videos of the night sky show the stars and sky moving above a steady Earth. Here, however, the frames have been digitally rotated so that it is the stars that stay (approximately) steady, and the Earth that moves beneath them.

Comets and Bright Star
6.01.2016

This timely, telescopic, two panel mosaic spans about 10 full moons across planet Earth's predawn skies. Recorded as the year began from Tenerife, Canary Islands, near the top of the frame are the faint coma and tail of Comet Borrelly (P/19).

APOD: 2026 March 26 Б
26.03.2026

What is the sound of two black holes merging in deep space? Sound waves don't propagate in vacuum, but gravitational waves do. In 2015 we were able to "hear" them for the first time and confirm one of Albert Einstein's theoretical predictions.

Two Black Holes Merge
12.02.2016

Just press play to watch two black holes merge. Inspired by the first direct detection of gravitational waves by LIGO, this simulation video plays in slow motion but would take about one third of a second if run in real time.

Why Stars Twinkle
25.07.2000

This is what a star really looks like from the surface of the Earth. To the best the human eye can see, stars are so far away they appear the same as would infinitesimal points of light.

Tyrrhenian Sea and Solstice Sky
21.12.2010

Today the solstice occurs at 23:38 Universal Time, the Sun reaching its southernmost declination in planet Earth's sky. Of course, the December solstice marks the beginning of winter in the northern hemisphere and summer in the south.

Celestial Trails over Greece
4.05.2011

If you watch the horizon at just the right place and at just the right time, you can witness some spectacular juxtapositions between Earth and sky. In the above video, stars, the Moon, and even a partially eclipsed Sun were recorded rising and setting over photogenic landmarks in Greece.

NGC 7635: The Bubble Nebula
19.04.2018

Blown by the wind from a massive star, this interstellar apparition has a surprisingly familiar shape. Cataloged as NGC 7635, it is also known simply as The Bubble Nebula. Although it looks delicate, the 7 light-year diameter bubble offers evidence of violent processes at work.

Orion over the Central Bohemian Highlands
18.02.2020

Do you recognize this constellation? Setting past the Central Bohemian Highlands in the Czech Republic is Orion, one of the most identifiable star groupings on the sky and an icon familiar to humanity for over 30,000 years.

Ninety Gravitational Wave Spectrograms and Counting
7.12.2021

Every time two massive black holes collide, a loud chirping sound is broadcast out into the universe in gravitational waves. Humanity has only had the technology to hear these unusual chirps for the past seven years, but since then we have heard about 90 -- during the first three observing runs.