Equinox on a Spinning Earth
21.09.2021

When does the line between night and day become vertical? Today. Today is an equinox on planet Earth, a time of year when day and night are most nearly equal. At an equinox, the Earth's terminator -- the dividing line between day and night -- becomes vertical and connects the north and south poles.

Dust Storm on Planet Earth
2.03.2000

From low Earth orbit, NASA's SeaWIFS instrument records ocean color, tracking changes in our water world's climate and biosphere. But even an ocean planet can have dust storms. On February 26th, SeaWIFS...

Orion Launch
5.12.2014

Headed for two orbits of planet Earth and a splashdown in the Pacific, Orion blazed into the early morning sky on Friday at 7:05am ET. The spacecraft was launched atop a United Launch Aliance Delta IV Heavy rocket from Cape Canaveral Air Force Station in Florida.

Home from Above
14.11.2010

There's no place like home. Peering out of the windows of the International Space Station (ISS), astronaut Tracy Caldwell Dyson takes in the planet on which we were all born, and to which she would soon return.

Mars Approach
31.05.2018

Since the distance from Earth to Mars changes drastically as the planets orbit the Sun, Mars' appearance changes dramaticaly. Mars is bright now, and it's getting closer and brighter still as it orbits toward its 2018 opposition and closest approach to Earth in late July.

Phases of Venus
16.03.2017

Just as the Moon goes through phases, Venus' visible sunlit hemisphere waxes and wanes. This composite of telescopic images illustrates the steady changes for the inner planet, seen in the west as the evening star, as Venus grows larger but narrows to a thin crescent from December 20, 2016 through March 10.

Saturn from Above
5.03.2007

This image of Saturn could not have been taken from Earth. No Earth based picture could possibly view the night side of Saturn and the corresponding shadow cast across Saturn's rings. Since Earth is much closer to the Sun than Saturn, only the day side of the planet is visible from the Earth.

An Annular Eclipse of the Sun
24.08.1998

An annular eclipse of the Sun was visible in parts of the Eastern Hemisphere on Saturday. The above picture was taken at that time by a video camera in Mersing on the East Coast of Malaysia and emailed to APOD yesterday from an internet cafe in Kuala Lumpur.

Supernova 1987a Aftermath
21.06.1995

In 1987 a star in one of the Milky Way's satellite galaxies exploded. In 1994 the Hubble Space Telescope, in orbit around the earth, took a very detailed picture of the remnants of this explosion. This picture, above, showed unusual and unexpected rings, and astronomers are not sure how they formed.

Big Mars from Hubble
27.08.2003

At about 10 am Universal Time today, Mars and Earth will pass closer than in nearly 60,000 years. Mars, noticeably red, will be the brightest object in the eastern sky just after sunset.