The title of the post is definitely confusing. Why would anyone want to look at the moon and miss the beautiful and rare sight of Venus moving across the sun (Transit of Venus)? This is equivalent to a car racing fan admiring the beauty of a normal road car when a Formula 1 car is parked right next to it. No astronomer would want to do that, especially using a billion dollar telescope like Hubble. Then why is NASA planning to do this?
If you have read my post titled "Astronomers confirm the presence of life on Earth", the most popular post on my blog, you already know the answer. But let me quickly summarize the experiment the astronomers are trying to perform during the transit of Venus.
The Kepler mission is a exoplanet search mission based on the transit method (to know more about exoplanet search, do read this article). The Kepler probe searches for exoplanets by monitoring the brightness of distant stars. When an exoplanet comes in between us and the star, there is a small dip in the brightness of the star. Based on this change in brightness the size and the distance of the exoplanet from its star can be calculated. But the change in brightness is extremely small due to which the probe has to be calibrated to achieve very high sensitivity.
Astronomers are currently planning to use the same transit method to look at the transit of Venus and obtain information that could be used to calibrate the Kepler probe. But there is a small problem. From Earth, the sun is a really bright star when compared to the other distant stars that Kepler monitors. So in order to test the transit method for stars that appear dim, astronomers require a dimmer source of light. Sunlight reflected by the moon is an excellent source of dim light. This is why NASA is planning to point the Hubble Space Telescope to the moon during the transit of Venus. Astronomers are going to see if the transit of Venus is visible in the sunlight reflected by the moon.
Apart from observing the transit, astronomers are also interested in looking at the small amount of light that passes through the atmosphere of Venus as this light contains information about its composition of the atmosphere of Venus. So if the signature of the atmosphere of Venus can be identified in the sunlight reflected from the moon, astronomers could extrapolate this experiment to identify the composition of exoplanets. This could give us an indication of the presence or absence of life in these planets (for more information on life on exoplanets, read this article).
The transit of Venus, on June 5-6 this year, is cool not only because of this experiment but also because of the fact that this is the last transit till the year 2117. So make sure that you watch it either directly or via live streaming on several websites. For more information about the transit, read this article by Phil Plait.
Though I would encourage everyone to observe the transit, safety while observation is extremely important. Hence I will make this very clear - PLEASE DO NOT LOOK AT THE SUN DIRECTLY, EITHER WITH THE NAKED EYE OR WITH A TELESCOPE.
Astronomers are currently planning to use the same transit method to look at the transit of Venus and obtain information that could be used to calibrate the Kepler probe. But there is a small problem. From Earth, the sun is a really bright star when compared to the other distant stars that Kepler monitors. So in order to test the transit method for stars that appear dim, astronomers require a dimmer source of light. Sunlight reflected by the moon is an excellent source of dim light. This is why NASA is planning to point the Hubble Space Telescope to the moon during the transit of Venus. Astronomers are going to see if the transit of Venus is visible in the sunlight reflected by the moon.
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| Credit: NASA, ESA, and A. Feild (STScI) |
The transit of Venus, on June 5-6 this year, is cool not only because of this experiment but also because of the fact that this is the last transit till the year 2117. So make sure that you watch it either directly or via live streaming on several websites. For more information about the transit, read this article by Phil Plait.
Though I would encourage everyone to observe the transit, safety while observation is extremely important. Hence I will make this very clear - PLEASE DO NOT LOOK AT THE SUN DIRECTLY, EITHER WITH THE NAKED EYE OR WITH A TELESCOPE.
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