Far Side of the Sun
3.05.2001

You may think it's impossible to see through the Sun, but maps of the Sun's far side are now made routinely by instruments on board the sun-staring SOHO spacecraft. This is one such map from April 12.

Julius Caesar and Leap Days
29.02.1996

Today, February 29th, is a leap day - a relatively rare occurrence. Advised by Alexandrian astronomer Sosigenes, Roman dictator Julius Caesar, pictured above in a self-decreed minted coin, created a calender system in 46 BC that contained one leap day every four years.

Tagging Bennu: The Movie
3.11.2020

This is what it looks like to punch an asteroid. Last month, NASA's robotic spacecraft OSIRIS-REx descended toward, thumped into, and then quickly moved away from the small near-Earth asteroid 101955 Bennu. The featured video depicts the Touch-And-Go (TAG) sampling event over a three-hour period.

Active Regions, CMEs, and X Class Flares
8.06.2000

Space Weather forcasters are predicting major storm conditions over the next few days as the active Sun has produced at least three strong flares and a large coronal mass ejection (CME) since Tuesday, June 6th.

APOD: 2020 July 22 Б The Structured Tails of Comet NEOWISE
22.07.2020

What is creating the structure in Comet NEOWISE's tails? Of the two tails evident, the blue ion tail on the left points directly away from the Sun and is pushed out by the flowing and charged solar wind.

Simulation: A Disk Galaxy Forms
17.07.2012

How do galaxies like our Milky Way form? Since our universe moves too slowly to watch, faster-moving computer simulations are created to help find out. Green depicts (mostly) hydrogen gas in the above movie, while time is shown in billions of years since the Big Bang on the lower right.

An ALMA Telescope Array Time Lapse
26.05.2014

It is the most expensive and complex ground-based astronomy project ever -- what will it see tonight? The Atacama Large Millimeter Array (ALMA) project consists of 66 dishes, many the size of a small house, situated in the high altitude Atacama Desert in Northern Chile.

Highest, Tallest, and Closest to the Stars
25.02.2016

Fans of planet Earth probably recognize its highest mountain, the Himalayan Mount Everest, on the left in this 3-panel skyscape of The World at Night. Shrouded in cloud Everest's peak is at 8,848 meters (29,029 feet) elevation above sea level.

Gravel Ejected from Asteroid Bennu
16.09.2020

Why does asteroid Bennu eject gravel into space? No one is sure. The discovery, occurring during several episodes by NASA's visiting ORISIS-REx spacecraft, was unexpected. Leading ejection hypotheses include impacts by Sun-orbiting meteoroids, sudden thermal fractures of internal structures, and the sudden release of a water vapor jet.