Mercury: what a hot and bothered place...

For research on Mercury, please see the following web sites:

While you explore those pages, find the answers to the following questions:
  1. What is the name of the only spacecraft sent from Earth to study Mercury?
  2. Earth's Moon is "tidally locked" with Earth, meaning that it always keeps the same face pointing towards Earth. This also means the Moon's period of rotation (time it takes to spin once) is equal to its period of revolution (how long it takes to go around Earth once).
    TRUE or FALSE: Mercury, the closest planet to the Sun, is tidally locked with the Sun, so its period of rotation is equal to its period of revolution.

 

Mercury Tidbits

(adapted from http://pds.jpl.nasa.gov/planets/welcome/mercury.htm)

  • Mercury's orbit is highly eccentric-- at perihelion it is only 46 million km from the Sun but at aphelion it is 70 million!

  • The fact that Mercury rotates three times in two of its years combined with the high eccentricity of its orbit would produce very strange effects for an observer standing on Mercury. At some longitudes the observer would see the Sun rise and then gradually increase in apparent size as it slowly moved toward the zenith. At that point the Sun would stop, briefly reverse course, and stop again before resuming its path toward the horizon and decreasing in apparent size. All the while the stars would be moving three times faster across the sky than as seen from Earth. Observers at other points on Mercury's surface would see different but equally bizarre motions.

 

Temperature variations on Mercury are the most extreme in the solar system ranging from 90 K to 700 K. The temperature on Venus is slightly hotter but very stable.

Nineteenth century astronomers could not adequately explain Mercury's orbital parameters using Newtonian mechanics. The tiny differences between the observed and predicted values were a minor but nagging problem for many decades. Some thought that another planet (sometimes called Vulcan) might exist in an orbit near Mercury's to account for the discrepancy. The real answer turned out to be much more dramatic: the equivalence of gravity with warping of spacetime--Einstein's General Theory of Relativity! Its correct prediction of the motions of Mercury was an important factor in the early acceptance of the theory.

image of mercury

to questions about Mercury.