Yet more planet transits

Posted by Emily Lakdawalla

2012/06/14 11:00 CDT

Topics: transit of Venus, astronomy, planetary astronomy

Last week, I posted a guest blog entry from astronomer Jay Pasachoff about observing Venus transits from Jupiter and Saturn later this year. A reader, Mike, responded with a question: "What about also looking at transits by Earth and Mars from Jupiter, and transits by Earth, Mars, and Jupiter from Saturn?" I thought that was a very good question and sent that and a few others back to Jay.

So: Are there more transits of more planets as seen from other planets? Yes. In the time period between 2012 and 2117 (the year of the next Venus transit as seen from Earth), Jupiter will see Venus transit the Sun 15 times, and Earth transit 10 times. Saturn will see 21 Venus and 6 Earth transits. Here's a few notable upcoming transits:

Transit of Venus as seen from Jupiter: September 20, 2012, and then not until May 26, 2024
Transit of Earth as seen from Jupiter: January 5, 2014 and then not until January 10, 2026
Transit of Venus as seen from Saturn: May 6 and December 21, 2012 and then not until: January 14, 2028
Transit of Earth as seen from Saturn: July 20, 2020
Transit of Mars as seen from Saturn: May 17, 2024
Transit of Jupiter as seen from Saturn: not until March 17, 7571!

Why is a transit of Venus particularly interesting? Jay explained that transits of both Venus and Earth are most interesting because of their atmospheres. The goal is to see if we can detect Venus' and Earth's atmospheres as they transit, because we'd like to use similar techniques to detect atmospheres around Earth-size planets orbiting other stars. Jay now reports that their proposal to observe the next transit of Venus as seen from Jupiter with Hubble was turned down; it is very competitive to get time on Hubble. He said they intend to apply again to observe the January 5, 2014 transit of Earth as seen from Jupiter.

Comments:

Michael: 06/14/2012 11:17 CDT

The Hubble Space Telescope is in orbit around the Earth. Could you explain how one could use it to observe a transit of Earth, as seen from Jupiter?

Callie: 06/14/2012 12:15 CDT

"In January 2014, Jupiter will witness a transit of Earth. And we can see it too, the astronomers say, by training NASA's Hubble Space Telescope on the huge planet and studying the sunlight it reflects." http://www.msnbc.msn.com/id/47682611/ns/technology_and_science-space/t/hubble-telescope-may-see-rare-transit-earth/#.T9obbitYsVc

Stephen: 06/14/2012 02:33 CDT

The HST looked at the Moon for spectroscopic changes due to the atmosphere of Venus. The surface of Jupiter has ever changing clouds, so that doesn't seem to be a possible answer. But Jupiter has three big moons that would be better candidates. And, as they're tide locked to Jupiter, before and after shots should be fairly easy.

abramson: 06/14/2012 10:28 CDT

And what about Venus transit of Jupiter as seen from Earth in 2065? Cool! http://en.wikipedia.org/wiki/Astronomical_transit#Mutual_planetary_transits_and_occultations

Christian: 06/15/2012 02:21 CDT

Sorry, but I am missing something obvious. With all the probes and other devices we have on/near Mars, what about transits from Earth and Venus as seen from Mars ?

Emily: 06/21/2012 09:29 CDT

Because they're using sunlight reflected off of other obejcts to look for the dimming, this doesn't work from Mars. No spacecraft has a full-disk view of Mars, and its moons are too dim, small, and fast-moving to serve as reflectors the way Jupiter's can.

Ben H.: 07/08/2012 11:50 CDT

Do you have a full list of all those upcoming transits? I was interested in whether any of them are at a time period that humans might see them from that location. The ones you have listed are way too soon, and no humans will be at Jupiter or Saturn by then. - Ben