Related topics: nasa · satellite · earth · solar system · spacecraft

Curiosity Rover finds high levels of methane on Mars

A team working with NASA to study data the Mars Curiosity Rover has found high levels of methane at a site on the Red Planet. The existence of methane is, of course, a possible sign of life, since it is produced in abundance ...

The low density of some exoplanets is confirmed

The Kepler mission and its extension, called K2, discovered thousands of exoplanets. It detected them using the transit technique, measuring the dip in light intensity whenever an orbiting planet moved across the face of ...

Small satellite concept finalists target moon, Mars and beyond

NASA has selected three finalists among a dozen concepts for future small satellites. The finalists include a 2022 robotic mission to study two asteroid systems, twin spacecraft to study the effects of energetic particles ...


In physics, an orbit is the gravitationally curved path of one object around a point or another body, for example the gravitational orbit of a planet around a star.

Historically, the apparent motion of the planets were first understood in terms of epicycles, which are the sums of numerous circular motions. This predicted the path of the planets quite well, until Johannes Kepler was able to show that the motion of the planets were in fact elliptical motions.[citation needed] Isaac Newton was able to prove that this was equivalent to an inverse square, instantaneously propagating force he called gravitation.[citation needed] Albert Einstein later was able to show that gravity is due to curvature of space-time, and that orbits lie upon geodesics. This is the current understanding.

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