The transit of Venus can't be observed with the Hubble Space Telescope because the extreme brightness of the sun would destroy the telescope and its instruments.

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At this point in space, the gravity of the Earth and the Sun act in such a way that the telescope will be stationary relative to the Earth and Sun.

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Scientists have recorded the sound of three stars similar to our Sun using France's Corot space telescope.

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During the eight days and 22 hours the mission is scheduled to run--eight days and 17 hours more than Glenn got last time--the astronauts will be kept busy releasing and retrieving a sun-sensing satellite, testing components for the Hubble Space Telescope, and conducting experiments in an onboard laboratory.

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"The observations were made shortly after sunrise before the Sun's heating of the atmosphere distorted the images captured by the telescope, " says Michael Mendillo, professor of astronomy at Boston University.

BBC: Close up on Mercury

They concluded that the black drop results from blurring of the image (whether from Earth's atmosphere, or inevitable imperfections of the telescope) combined with the way that the disc of the sun fades in brightness towards its rim.

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Opportunities to photograph Mercury from space are also limited because light sensitive equipment, such as the Hubble Space Telescope, are not allowed to look at objects close to the Sun, such as Mercury or Venus.

BBC: Close up on Mercury