December 16, 2012

Two Earth's Satellites viewed from Houston

This photograph taken from Houston, Texas, juxtaposes Earth’s oldest satellite with one of its youngest. The Moon is thought to have been formed by the impact of a large body (perhaps Mars-sized) with the early Earth approximately 4.6 billion years ago. In contrast, the first components of the International Space Station (ISS) assumed orbit around the Earth in 1998, with assembly completed 13 years later—a significant period of time to us, but the merest fraction of a second in the history of the Moon.

While the ISS appears to be fairly close to the Moon’s surface in the image, it’s a trick of perspective. The Moon orbits Earth at an average distance of 384,400 kilometers (238,855 miles), while the ISS orbits at altitudes ranging from approximately 330 to 410 kilometers (205 to 255 miles).

The ISS can frequently be viewed from the Earth’s surface with the naked eye as a bright object moving rapidly across the sky. The ISS has also been photographed from Earth transiting more dramatic backdrops, such as the Sun.
As can be seen in the high-resolution version of this image, major structural elements of the Station—such as the solar panel arrays—can be resolved using high-powered binoculars or lenses. Major features of the lunar nearside surface are likewise discernable with the naked eye, the most obvious being the dark maria lowlands (mare in plural) contrasting with the bright highland regions (or terrae). With moderate magnification, other features such as impact craters become clearly visible; for example, Copernicus and Tycho Craters.

Image Credit: NASA
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