Mercury: what a hot and bothered place...
For research on Mercury, please
see the following web sites:
you explore those pages, find the answers to the following
- What is the name of the only spacecraft sent from
Earth to study Mercury?
- 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
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'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
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.
to questions about Mercury.