Mercury is the first planet and the closest to the sun in our Solar System. Even Though it is the closest it is not the hottest. Venus is the hottest due to it's dense atmosphere. The surface temperature varies from -173 to 427 Celsius. It's orbital period is 87.97 Earth days. It has no moons. Since Mercury can be seen without the need of a telescope, many ancient civilizations saw the planet, and as such it is impossible to determine who discovered it first. However, it was first observed with the help of a telescope in early 17th century, by Galileo Galilei. Galileo’s crude telescope didn’t manage to capture Mercury’s phases, this would be observed later by astronomer Giovanni Zupi in 1639, and thus he discovered that the planet had similar phases like Venus and the Moon.
Here are a few interesting facts:
Despite its closeness to the Sun, it is not the hottest planet, that title belongs to Venus.
Mercury is the fastest planet, completing a trip around the Sun in 88 Earth days.
It orbits around the Sun with a speed of about 47 KMPS(Yup, it's km per second).
It is the smallest terrestrial planet from the Solar System, and in fact the smallest of all the planets.
It is the second densest planet in the Solar System, with a density of 5.43 g/cm³.
Mercury spins slowly on its axis and completes one rotation every 59 Earth days. One Mercury solar day or one full day-night cycle, equals 176 Earth days—just over two years on Mercury. Yup a day in mercury is longer than a year!
Instead of an atmosphere, Mercury possesses a thin exosphere made up of atoms blasted off the surface by the solar wind and striking meteoroids. Mercury's exosphere is composed mostly of oxygen, sodium, hydrogen, helium and potassium.
During the day the temperature can reach up to 427 Celsius while at night it will be at -173 Celsius.
Mercury rotates in a way that is unique in the Solar System. It is tidally locked with the Sun in a 3:2 spin-orbit resonance.
Mercury and Venus orbit the Sun within Earth’s Orbit, this makes them inferior planets.
It is theorized that Mercury was formed about 4.5 billion years ago when gravity pulled swirling gas and dust together to form the small planet. Its small size but enormous core is theorized to be the result of a collision with another giant object that stripped much of its surface.
The diagram beside illustrates the effects of the eccentricity, showing Mercury’s orbit overlaid with a circular orbit having the same semi-major axis. The resonance makes a single solar day on Mercury last exactly two Mercury years, about 176 Earth days.
Have a look below for more details for Mercury.
Source: nineplanets.org ; wikipedia.com ; universetoday.com
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