Speaking of Hubble...

Mirror, Mirror in the Sky

September 7, 2012 by Frank Summers
Jupiter could be the next test subject for analyzing light from a Venus transit.

Jupiter could be the next test subject for analyzing light from a Venus transit.

My blog post of May 25, 2012 was titled “Examining Venus in a Lunar Mirror.” In that piece, I described how Hubble would attempt to observe the transit of Venus on June 5, 2012.

The idea is that, since Hubble cannot directly observe the Sun, one could look at the Sun’s light reflected off of the Moon. A detailed analysis might be able to separate out the signature of light that passed through Venus’ atmosphere. The observation would be a proxy for studying the atmospheres of extrasolar planets that happen to transit their star from our point of view. Venus, with a known atmosphere, could serve as calibration for the unknown atmospheres of extrasolar planets.

Sad to say, the Hubble observations were a failure. Not every science experiment goes as planned. Well, actually, this observation went as planned, but the planning was incorrect. A miscalculation in positions meant that the observation did not capture what had been intended.

But science is an enterprise where learning from failure is not just possible, it is one of the main methods of advancing the field. For all the triumphs and breakthroughs that are celebrated, there are a thousand times more investigations that uncovered modest, incomplete, or dead-end results. That work invariably builds the foundation and shapes the blueprints for the eventual discovery.

In this case, the lesson is to think bigger: Don’t just take our Earth-bound perspective, consider things from a solar system perspective. The next transit of Venus as seen from Earth will be in December 2117, but the next Venus transit visible in our solar system will be on September 20, 2012 – seen from Jupiter.

A proposal has been put forward for Hubble to observe Jupiter, both before and during this transit, to perform a study of the Venusian atmosphere in reflected light similar to Hubble’s Venus transit Moon observations.

Perhaps more exciting, Earth itself will transit the Sun as seen from Jupiter on January 5, 2014. What could be a better test of looking for Earth-like planets elsewhere than to study our own planet in an analogous fashion? Mirror, mirror in the sky, Hubble watches Jupiter as Earth passes by.

Opportunity arises from understanding one’s mistakes. It is a great lesson in science and in all of life’s pursuits.