Valles Marineris: The Grand Canyon of Mars
29.05.2016

Mars will look good in Earth's skies over the next few days -- but not this good. To get a view this amazing, a spacecraft had to actually visit the red planet. Running across the image center, though, is one the largest canyons in the Solar System.

The Helix Nebula from CFHT
3.01.2018

Will our Sun look like this one day? The Helix Nebula is one of brightest and closest examples of a planetary nebula, a gas cloud created at the end of the life of a Sun-like star.

The Unusual Boulder at Tychos Peak
7.05.2018

Why is there a large boulder near the center of Tycho's peak? Tycho crater on the Moon is one of the easiest features to see, visible even to the unaided eye (inset, lower right). But at the center of Tycho (inset, upper left) is a something unusual -- a 120-meter boulder.

The Voyagers' Message in a Bottle
31.08.2002

Launched twenty-five years ago, NASA's Voyager 1 and 2 spacecraft are now over 10 billion kilometers from the Sun. Still operational, the Voyagers are being tracked and commanded through the Deep Space Network.

A Year of Assessing Astronomical Hazards
31.12.2002

Could an asteroid destroy civilization on Earth? Mountain-sized space rocks could potentially impact the Earth causing global effects, and perhaps even be mistaken for a nuclear blast of terrestrial origin. Such large impacts are rare but have happened before. Modern telescopes have therefore begun to scan the skies for signs of approaching celestial hazards.

Noctilucent Clouds and Aurora Over Scotland
19.08.2013

Why would the sky still glow after sunset? Besides stars and the band of our Milky Way galaxy, the sky might glow because it contains either noctilucent clouds or aurora. Rare individually, both are visible in the above time lapse movie taken over Caithness, Scotland, UK taken during a single night earlier this month.

Ou4: A Giant Squid Nebula
18.07.2014

A mysterious, squid-like apparition, this nebula is very faint, but also very large in planet Earth's sky. In the mosaic image, composed with narrowband data from the 2.5 meter Isaac Newton Telescope, it spans some 2.5 full moons toward the constellation Cepheus.

Mars Rover at Victoria Crater Imaged from Orbit
9.10.2006

An unusual spot has been found on Mars that scientists believe is not natural in origin. The spot appears mobile and is now hypothesized to be a robot created by an intelligent species alien to Mars. In fact, the spot appears to be NASA's robotic Opportunity rover currently rolling across Mars.

APOD: 2023 December 5 Б Energetic Particle Strikes the Earth
5.12.2023

It was one of the most energetic particles ever known to strike the Earth -- but where did it come from? Dubbed Amaterasu after the Shinto sun goddess, this particle, as do all cosmic rays...

APOD: 2026 August 4 Б Curious Cometary Knots in the Helix Nebula
4.08.2026

What causes unusual knots of gas and dust in planetary nebulas? Seen also in the Ring Nebula, the Dumbbell Nebula and NGC 2392, the knots' existence was not initially predicted, and their origins are still not well understood.