A Meteor and the Gegenschein
12.05.2021

Is the night sky darkest in the direction opposite the Sun? No. In fact, a rarely discernable faint glow known as the gegenschein (German for "counter glow") can be seen 180 degrees around from the Sun in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles.

The Shifting Tails of Comet NEOWISE
12.08.2020

Keep your eye on the ion tail of Comet NEOWISE. A tale of this tail is the trail of the Earth. As with all comets, the blue ion tail always points away from the Sun. But as Comet C/2020 F3 (NEOWISE) rounded our Sun, its ion tail pointed in slightly different directions.

Orion Dawn Over Mount Nemrut
16.12.2008

What's that in front of Orion? Forty kilometers north of Kahta, Turkey, lies Mount Nemrut, a mountain adorned with the fragments of vast statues built over 2000 years ago. The stone sculptures once...

Astronaut Exploring: An Apollo 15 Panorama
11.11.2018

What would it be like to explore the Moon? NASA's Apollo missions gave humans just this chance in the late 1960s and early 1970s. In particular, the Apollo 15 mission was dedicated to better understanding the surface of the Moon by exploring mountains, valleys, maria, and highlands.

A Galaxy Beyond Stars, Gas, Dust
19.10.2022

Do we dare believe our eyes? When we look at images of space, we often wonder whether they are "real", and just as often the best answer varies. In this case, the scene appears...

Sunrise Analemma
20.03.2003

Astronomically speaking, at the Equinox on March 21, 01:00 UT (March 20, 8:00 PM ET) the season changes. For this Equinox the Sun rises due east as it crosses the celestial equator heading north. In celebration, consider this spectacular sunrise analemma!

An Apollo 15 Panorama: Astronaut Exploring
30.11.2008

What would it be like to explore the Moon? NASA's Apollo missions gave humans just this chance in the late 1960s and early 1970s. In particular, the Apollo 15 mission was dedicated to better understanding the surface of the Moon by exploring mountains, valleys, maria, and highlands.

The Topography of Mars
28.06.2001

Mars has its ups and downs. Visible on the above interactive topographic map of the surface of Mars are giant volcanoes, deep valleys, impact craters, and terrain considered unusual and even mysterious. Particularly notable...

Vesta Trek: A Digital Model of Asteroid Vesta
21.04.2015

You can explore asteroid Vesta. Recently, NASA's robotic spaceship Dawn visited Vesta, the second largest object in our Solar System's main asteroid belt, which lies between Mars and Jupiter. During a year-long stopover, Dawn's cameras photographed Vesta's entire surface, documenting all of the minor planet's major mountains and craters.

Halo of the Cat s Eye
20.10.2018

Not a Falcon 9 rocket launch after sunset, the Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its haunting symmetries are seen in the very...