Apart from the mechanical devices made of metal, wood or ivory, some early astronomers relied on massive masonry structures for astronomic...

This image shows the potentially hazardous near-Earth object 1998 KN3 as it zips past a cloud of dense gas and dust near the ...

NASA's Mars Science Laboratory rover Curiosity appears as a bluish dot near the lower right corner of this enhanced-color view from t...

Ten years after a Delta II rocket launched NASA's Spitzer Space Telescope, lighting up the night sky over Cape Canaveral, Fla., th...

Q 236: Question of the Day - 16 April 2013 (Week 16) What is Hubble Constant?

A235: The horizon is an imaginary circle that delimits the sky and the Earth, or an extension of the plane of the observer (at an altitude...

These illustrations, taken from computer simulations, show a swarm of dark matter clumps around our Milky Way galaxy. Image released J...

This cool space wallpaper shows a perspective view of a 50 km diameter crater in Thaumasia Planum. The image was made by combining dat...

An infrared sensor that could improve NASA's future detecting and tracking of asteroids and comets has passed a critical design test.

The object in this image is Jonckheere 900 or J 900, a planetary nebula — glowing shells of ionized gas pushed out by a dying star. Disc...

The soft glow in this image is NGC 2768, an elliptical galaxy located in the northern constellation of Ursa Major (The Great Bear). NG...

Q 235: Question of the Day - 15 April 2013 (Week 16) What is horizon?

Canada's automated aurora camera tweeted this photo on March 17, 2013

A234: The heliopause is the boundary of the heliosphere of the Sun in which the solar wind's density decreases greatly (and its speed ...

An unpiloted Russian Progress cargo ship departed the International Space Station early Monday, clearing the way for the arrival of th...

Q 234: Question of the Day - 12 April 2013 (Week 15) What is Heliopause?

A233: The HD (Henry Draper) number is an identifying number assigned to the strs in the Henry Draper catalog. In this system, every star i...

JP Brahic took this photo from France on April 5, 2013. He used a refractor Astro-Physics 155mm F/D 8.5 and a Bassler ACA1300 camera wi...

NASA's Solar Dynamics Observatory captured this image of an M6.5 class flare at 3:16 EDT on April 11, 2013. This image shows a comb...

The change of seasons on Titan is creating new cloud patterns at Titan's south pole. Here, a combination of red, green and blue im...