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Cool pic of comet Siding Spring near Mars

This composite NASA Hubble Space Telescope image captures the positions of comet Siding Spring and Mars in a never-before-seen close passage of a comet by the Red Planet, which happened at 2:28 p.m. EDT October 19, 2014. Image credit: NASA, ESA, PSI, JHU/APL, STScI/AURA

This composite NASA Hubble Space Telescope image captures the positions of comet Siding Spring and Mars in a never-before-seen close passage of a comet by the Red Planet, which happened at 2:28 p.m. EDT October 19, 2014. Image credit: NASA, ESA, PSI, JHU/APL, STScI/AURA

This composite NASA Hubble Space Telescope image captures the positions of comet Siding Spring and Mars in a never-before-seen close passage of a comet by the Red Planet, which happened at 2:28 p.m. EDT October 19, 2014. The comet passed by Mars at approximately 87,000 miles (about one-third of the distance between Earth and the moon). At that time, the comet and Mars were approximately 149 million miles from Earth.

When can you see Earth’s shadow?

Night falls when the part of Earth you’re standing on enters Earth’s shadow. Click here to expand this image. Image via NASA

At yesterday’s solar eclipse, the moon’s shadow brushed Earth. But what about Earth’s shadow? You can see it any clear evening. Just like you or me, Earth casts a shadow. Earth’s shadow extends millions of miles into space, in the direction opposite the sun.

Star of the week: Deneb Kaitos is the Sea-Monster’s Tail

Deneb Kaitos ranks as the most brilliant star in the constellation Cetus the Whale. This star shines on par with Polaris the North Star. There is a famous variable star also in Cetus, called Mira. And Mira might sometimes brighten up enough to match Deneb Kaitos, though only extremely rarely. Mira typically remains much too faint to see with the unaided eye while, as seen from mid-latitudes in the Northern Hemisphere, Deneb Kaitos soars highest in the southern sky in autumn.

This date in science: First-ever photo of Earth from space

Photo credit: White Sands Missile Range/Applied Physics Laboratory

First photo of Earth from space, October 24, 2916, via White Sands Missile Range/Applied Physics Laboratory

October 24, 1946. Were you alive at a time when we’d never seen Earth from space? Not many of us were, and it’s hard to imagine. But if you can imagine it, think how you’d have felt seeing this first-ever photograph of Earth from outer space, taken on today’s date in 1946. On this date, a group of soldiers and scientists in the New Mexico desert launched a V-2 rocket – fitted with a 35-millimeter motion picture camera – to a suborbital altitude of 105 kilometers (65 mi). The camera was destroyed after being dropped back to Earth, but the film survived.

See it! Photos of October 23 solar eclipse

October 23 partial solar eclipse from Jennifer Rose Lane in West Virginia.

October 23 partial solar eclipse from Jennifer Rose Lane in West Virginia.

Favorite photos of the beautiful partial solar eclipse on October 23. Thank you to all who submitted to EarthSky.org or posted at EarthSky Facebook or G+.

Close-up on constellation Perseus the Hero and Demon Star

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Tonight … just in time for the upcoming season of Halloween and the Day of the Dead … look for the Demon Star in the constellation Perseus the Hero. That star is Beta Persei, or Algol, pronounced AL-gul. The name Algol comes from an Arabic term for head of the ghoul or head of the demon.

Fake image of India during Diwali versus the real thing

This image of India has been circulating on the Internet for years. Some claim it shows India during Diwali, but it does not. It’s a real satellite image alright, but it’s composite image, with several different years of lighting combined together. Image via U.S. Defense Meteorological Satellite Program

Have you seen this image? It’s a fake.

The Hindu festival of Diwali celebrates the victory of Good over the Evil and Light over Darkness. It also marks the beginning of the Hindu New Year. Lighting lamps, candles, and fireworks are a big part of Diwali. It’s a celebration of light! But can you see those celebratory lights from space? The answer is no.

Starquake sets magnetar ringing like a bell

A rupture in the crust of a highly magnetized neutron star, shown here in an artist's rendering, can trigger high-energy eruptions. Fermi observations of these blasts include information on how the star's surface twists and vibrates, providing new insights into what lies beneath. Image via NASA's Goddard Space Flight Center/S. Wiessinger

Artist’s concept of the highly magnetized neutron star SGR J1550-5418. A rupture in its crust may have triggered high-energy blasts. Image via NASA’s Goddard Space Flight Center/S. Wiessinger

On January 22, 2009, NASA’s Fermi Gamma-ray Space Telescope detected rapid-fire, high-energy blasts from a magnetar – a neutron star with an exceedingly strong magnetic field. On October 21, 2014 – at the Fifth Fermi International Symposium in Nagoya, Japan – astronomers spoke of their work analyzing data from the 2009 event. They said they found underlying signals that might indicate a starquake on this magnetar that caused it to “ring like a bell.”

Video: 3D flight over Mars chaotic terrain

Get out your 3D glasses and watch a flyover of the weird landforms on Mars called ‘chaotic terrain.’

Sun may delay plans for sending humans to Mars

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View larger. | This illustration depicts the heliosphere, or sphere of the sun’s magnetic influence. Outside this sphere, there’s a large increase in galactic cosmic rays. Illustration via AGU

The human dream of travel to Mars and beyond seems closer than it’s ever been. But a new study announced by the American Geophysical Union on October 21 suggests that these plans might need to be delayed, or at least significantly altered. The reason? Increasing levels of cosmic radiation spurred by decreasing activity on our sun.