Posted on by Elizabeth Howell

Comet Siding Spring Was Bleeding Hydrogen As It Sped By Mars

As Comet Siding Spring passed close by Mars on Sunday (Oct. 19), NASA’s newest Mars spacecraft took a time-out from its commissioning to grab some ultraviolet pictures of its coma. What you see above is hydrogen, a whole lot of it, leaving the comet in this picture taken from 5.3 million miles (8.5 million kilometers).

The hydrogen is a product of the water ice on the comet that the Sun is slowly melting and breaking apart into hydrogen and oxygen molecules. Because hydrogen scatters ultraviolet light from the Sun, it shows up rather clearly in this picture taken by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft.

Check out more recent pictures of Siding Spring below.

Is this an image of Comet Siding Spring? It's the only fuzzy object in the field photographed on Sol 3817 (October 19) by the Opportunity Rover. Click for original raw image.
Is this an image of Comet Siding Spring? It’s the only fuzzy object in the field photographed on Sol 3817 (October 19) by the Opportunity Rover. Click for original raw image.
Comet Siding Spring near Mars in a composite image by the Hubble Space Telescope, capturing their positions between Oct. 18 8:06 a.m. EDT (12:06 p.m. UTC) and Oct. 19 11:17 p.m. EDT (Oct. 20, 3:17 a.m. UTC). Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA
Comet Siding Spring near Mars in a composite image by the Hubble Space Telescope, capturing their positions between Oct. 18 8:06 a.m. EDT (12:06 p.m. UTC) and Oct. 19 11:17 p.m. EDT (Oct. 20, 3:17 a.m. UTC). Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA
Another photo, just in, taken of the comet and Mars today (Oct. 19) by Rolando Ligustri. Beautiful!
Another photo, just in, taken of the comet and Mars today (Oct. 19) by Rolando Ligustri. Beautiful!
Comet 2013 A1 Siding Spring on October 17, 2014, with two days to go until its Martian encounter. Very dense Milkyway starfield in the background with many darker obscured regions. Credit and copyright: Damian Peach.
Comet 2013 A1 Siding Spring on October 17, 2014, with two days to go until its Martian encounter. Very dense Milkyway starfield in the background with many darker obscured regions. Credit and copyright: Damian Peach.

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