Sprite Lightning in Slow Motion
13.10.2014

What causes sprite lightning? Mysterious bursts of light in the sky that momentarily resemble gigantic jellyfish have been recorded for over 25 years, but their root cause remains unknown. Some thunderstorms have them -- most don't. Recently, however, high speed videos are better detailing how sprites actually develop.

Gamma ray Rain from 3C 279
22.07.2015

If gamma-rays were raindrops a flare from a supermassive black hole might look like this. Not so gently falling on the Fermi Gamma-ray Space Telescope from June 14 to June 16 the gamma-ray photons, with energies up to 50 billion electron volts, originated in active galaxy 3C 279 some 5 billion light-years away.

A Transit of Mercury
12.05.2016

On May 9, the diminutive disk of Mercury spent about seven and a half hours crossing in front of the Sun as viewed from the general vicinity of Earth. It was the second of 14 transits of the Solar System's innermost planet in the 21st century.

Comet PanSTARRS and the Helix Nebula
5.06.2016

It's rare that such different objects are imaged so close together. Such an occasion is occurring now, though, and was captured two days ago in combined parallel exposures from the Canary Islands of Spain.

Four Quasar Images Surround a Galaxy Lens
27.02.2017

An odd thing about the group of lights near the center is that four of them are the same distant quasar. This is because the foreground galaxy -- in the center of the quasar images and the featured image -- is acting like a choppy gravitational lens.

Starry Night by Jean Franцois Millet
13.03.2020

A dramatic nocturnal landscape from around 1850, this oil painting is the work of French artist Jean-Francois Millet. In the dark and atmospheric night sky are shooting stars, known too as meteors, above a landscape showing a path through the faintly lit countryside that leads toward trees and a cart in silhouette on the horizon.

Cosmic Latte: The Average Color of the Universe
27.12.2020

What color is the universe? More precisely, if the entire sky were smeared out, what color would the final mix be? This whimsical question came up when trying to determine what stars are commonplace in nearby galaxies. The answer, depicted above, is a conditionally perceived shade of beige. In computer parlance: #FFF8E7.

APOD: 2024 July 17 Б Villarrica Volcano Against the Sky
17.07.2024

When Vulcan, the Roman god of fire, swings his blacksmith's hammer, the sky is lit on fire. A recent eruption of Chile's Villarrica volcano shows the delicate interplay between this fire -- actually...

A Spiral Galaxy Gallery
14.03.1998

A progression of beautiful spiral galaxies is illustrated above with three photographs from NASA's Ultraviolet Imaging Telescope (UIT). Flying above the Earth's obscuring layer of atmosphere on the Space Shuttle Columbia during...

White Dwarf Star Spiral
1.06.2005

About 1,600 light-years away, in a binary star system fondly known as J0806, two dense white dwarf stars orbit each other once every 321 seconds. Interpreting x-ray data from the Chandra Observatory astronomers argue that the stars' already impressively short orbital period is steadily getting shorter as the stars spiral closer together.