Simulation: Two Black Holes Merge
10.05.2024

Relax and watch two black holes merge. Inspired by the first direct detection of gravitational waves in 2015, this simulation plays in slow motion but would take about one third of a second if run in real time. Set on a cosmic stage, the black holes are posed in front of stars, gas, and dust.

APOD: 2024 August 26 Б Perseid Meteors Over Inner Mongolia
26.08.2024

Did you see it? One of the more common questions during a meteor shower occurs because the time it takes for a meteor to flash is similar to the time it takes for a head to turn.

Mars to Appear Normal this August
8.08.2005

Will Mars appear extremely close and bright later this month? No. Regardless of numerous urban legends circulating, Mars will a relatively normal August. October is the best month to see Mars this year. The red planet is now visible in the morning before sunrise.

The Bloop: A Mysterious Sound from the Deep Ocean
27.04.2010

What created this strange sound in Earth's Pacific Ocean? Pictured above is a visual representation of a loud and unusual sound, dubbed a Bloop, captured by deep sea microphones in 1997. In the above graph, time is shown on the horizontal axis, deep pitch is shown on the vertical axis, and brightness designates loudness.

Coronal Rain on the Sun
27.05.2018

Does it rain on the Sun? Yes, although what falls is not water but extremely hot plasma. An example occurred in mid-July 2012 after an eruption on the Sun that produced both a Coronal Mass Ejection and a moderate solar flare. What was more unusual, however, was what happened next.

Neutrino Associated with Distant Blazar Jet
16.07.2018

With equipment frozen deep into ice beneath Earth's South Pole, humanity appears to have discovered a neutrino from far across the universe. If confirmed, this would mark the first clear detection of cosmologically-distant...

APOD: 2025 July 25 Б Twelve Years of Kappa Cygnids
25.07.2025

Meteors from the Kappa Cygnid meteor shower are captured in this time-lapse composite skyscape. The minor meteor shower, with a radiant not far from its eponymous star Kappa Cygni, peaks in mid-August, almost at the same time as the much better-known and better-observed Perseid meteor shower.

September Sky
29.09.2000

Star clusters, planets, and a red giant posed for this portrait of the night sky from rural Jasper County, Iowa, USA. Astrophotographer Stan Richard recorded the four minute time exposure looking east around midnight on September 3rd at Ashton-Wildwood Park.

Hubble Floats Free
6.03.1997

Why put observatories in space? Most telescopes are on the ground. On the ground, you can deploy a heavier telescope and upgrade it more easily. The trouble is that Earth-bound telescopes must look through the Earth's atmosphere.

Tutulemma: Solar Eclipse Analemma
22.12.2013

If you went outside at exactly the same time every day and took a picture that included the Sun, how would the Sun's position change? With great planning and effort, such a series of images can be taken. The figure-8 path the Sun follows over the course of a year is called an analemma.