Sun may delay plans for sending humans to Mars

Less solar activity indicates a weaker magnetic field on the sun. A weak field lets cosmic rays into the solar system, posing a radiation hazard for astronauts.

New 3D map of the cosmic web

A team of astronomers has created the first three-dimensional map of the adolescent universe, just 3 billion years after the Big Bang.

Video: Solar eclipse on October 23

Weather permitting, almost everyone in North America will be able to see the partial solar eclipse this Thursday.

Best photos: Comet Siding Spring sweeps past Mars

A sight never seen before in recorded history ... an encounter between Mars and a close-passing comet on October 19, 2014.

Comet Siding Spring’s near-miss of Mars was October 19

The close pass of Comet Siding Spring to Mars was exciting! Closest approach was October 19. Watch for photos from the event here at EarthSky.org.

Video: Comet Siding Spring’s close encounter with Mars

Here's a 2-minute video on the comet's October 19 near-miss of Mars, and how orbiting spacecraft will evade onslaught of dust particles from the comet.

Milky Way strips nearby galaxies of star-forming hydrogen

Astronomers have discovered that our nearest galactic neighbors are devoid of star-forming gas, and that our Milky Way is to blame.

What are super-Earths made of?

Astronomers struggle to learn about super-Earths - bigger than our Earth, smaller than Neptune - the most common type of planet found by the Kepler spacecraft.

Alright! Hubble finds potential targets for Pluto spacecraft

After a long search at the solar systems' fringes, scientists say they have three possible targets for the New Horizons spacecraft after its July 2015 Pluto flyby.

Spacecraft catches Mars atmosphere in act of escaping

Earth's atmosphere is leaking into space, too, but only very, very slowly. Meanwhile, Mars is thought to have lost much of its atmosphere already.

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