A humble moon sneaks by the biggest planet


Video made using images taken by NASA’s Solar Dynamics Observatory of the June 7 prominence eruption

A little more than a week ago I posted a must see video of a huge prominence eruption on the sun. Now you can watch it again in not one but four different wavelengths of ultraviolet light. The eruption appears to take only seconds, but we see it compressed in time. The event lasted some three hours – what a spectacle!

In this frame, Phobos and Jupiter are exactly aligned or in conjunction from the viewpoint of the Mars Express craft on June 1, 2011. Click the photo for a 3D version - don't forget your red-blue glasses! Credit: ESA/DLR/FU Berlin (G. Neukum)

Still earlier this month on June 1, the European Space Agency’s Mars Express craft, in orbit about the Red Planet since Christmas 2003, sent back a close-up photo of a conjunction of Mars’ moon Phobos with the planet Jupiter. Just released Friday, it’s certainly the first conjunction of its kind seen by earthlings. Diminutive Phobos is only 16 miles across, but at the moment the photo was taken, the craft was just 7,077 miles from the moon and 329 million miles from Jupiter. Being close counts when it comes to apparent size, which is why Phobos appears so much larger than the giant planet. Yet in spite of the millions of miles that separate them, you can still clearly see Jupiter’s equatorial belts of clouds. Amazing!


A movie of Phobos passing under Jupiter compiled from 104 still images.

Of course, the space agency had a more serious purpose that simply watching a conjunction, although we thank them for that. By knowing exactly where the spacecraft and Jupiter were located when Phobos swung by, the moon’s orbit could be further refined.

A slice of the carbonaceous chondrite NWA 3118 found in Morocco in 2003. The little round circles are chondrules, which grew from the original dust cloud in the early solar system. Credit: Mario Müller

Phobos is a heavily cratered, porous and very dark moon. Every planet and moon in the solar system absorbs certain colors of sunlight and reflects others. Based on the light Phobos reflects back to us, astronomers  have determined its composition is similar to a group of meteorites called the carbonaceous chondrites. As the name suggests, these meteorites are rich in carbon as well as water and clays. Some also contain amino acids, chemical compounds our DNA directs into the fashioning of proteins that build and sustain our bodies.

Artist's view of the early Earth still under bombardment by comets and meteorites. The moon was closer to our planet four billion years ago and rotated faster than it does today. Credit: Dr. David Aguilar

It’s a mighty leap from raw amino acids in meteorites to proteins, but amino acids brought to Earth by meteorites when our planet formed 4.6 billion years ago may have played a part in the origin of life. Add in comets, which scientists think contributed significant amounts of water to the cooling Earth, and you’ve got at least two key ingredients essential to life. How wonderful to think that these minor solar system bodies crashing onto our planet during its infancy may have been the stimulus for the life that’s unfolded since.

12 thoughts on “A humble moon sneaks by the biggest planet

    • Brandon, the next major meteor shower is the Perseids in mid-August. Every year in August we cross the orbit of Comet Swift-Tuttle and bits of grit, dust and ice from the comet’s tail and coma vaporize in the upper atmosphere as meteors. There are about a half dozen good showers every year. Our planet and its inhabitants are in no danger.

  1. ok now people will say that the star beteguese will explode and that will be terrible on the planet that what berda carter from austrila university of south queensland talking about it will do damage to the earth

    • Yes, it’s possible that Betelgeuse might explode as a supernova sometime in the future, but it’s distance of ~600 light years is large enough that it will not harm Earth. The star will become much brighter than it currently is, but not the “second sun” stuff circulating on the Internet. It will appear similar in brightness to a half moon — much brighter than Venus — but still appear as a point source in the sky. So imagine the half moon crunched down to a point and you’ve got it. Should be quite a marvel to see if it happens.

  2. and people still keep on talking about this is a brown dwarf this guy terral 03 on youtube is confident shouldnt we prepare to make sure

    • I am certain the temperature will drop and leaves will fall as we enter a new season. All the stuff about 2012 is more “end of the world” nonsense — or entertainment, depending on your point of view.

  3. ok i saw a video by terral 03 saying that he had an astronmer and they lookin at the brown dwarf and there was a person name 9nania who predict the earthquake in japan she on youtube to explain this bad weather

    • terral 03 and 9nania?? Honestly, I have a hard time taking people seriously who only go by their youtube names. Which astronomer was contacted, what are her/his credentials and what exactly did he/she say?

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