The continual movements of the planets around the sun cause the distance between Earth and Mercury to fluctuate. When both planets are on opposite sides of the sun, they can travel up to 137 million miles (222 million kilometers). But because of the orbit of Mercury, there is a difference every time it passes through either one of the two orbits of the sun. This distance varies from about 58 million miles (93.5 million kilometers) when Mercury is closest to Earth, to 76 million miles (123 million kilometers) when it is farthest away.
This distance changes over time as well. So the average distance between Earth and Mercury is constantly changing. The exact figure is difficult to calculate because we're dealing with such a large number, but it's estimated to be between 63 and 74 million miles (101 and 117 million kilometers).
Mercury has only been shown to have surface features so far. It was originally thought that the planet might be completely covered in ice, but this idea has since been ruled out. Scientists now believe that most of the planet is made up of iron and nickel with some silicon and oxygen thrown in for good measure.
It's also believed that there is water under the surface, although this has not been confirmed yet.
Mercury only makes a seven-year orbit around the sun. Astronomers utilized transit to determine the distance between the sun and Earth. During a transit, the planet passes directly across the face of the sun from our perspective on Earth.
Transits happen in pairs. We have now seen two transits of Mercury. The next will not be until 2039.
The angle that Mercury makes with the sun changes as it orbits the sun. On average, it is 24 degrees ahead of the sun at perihelion (the closest point to the sun) and 48 degrees behind at aphelion (the most distant point). But because of the eccentric nature of its orbit, this range is not constant. At some points during its orbit, Mercury is as close as 59 miles (95 km) from the sun! And at other times it is as far away as 74 million miles (119 million km).
During a transit, the brightness of the sun drops by about 15%. This is why there are no transits every year. Only when Mercury is near perihelion (or sometimes aphelion) can an observer see such a reduction. Otherwise, it would be too dark outside to observe one planet crossing another!
Planetary Radius from the Sun (in km) Distance in scientific notation Mercury 5.7909 x 10 57,909,00067,240,000 6.724 times ten equals 67,240,000 6.724 times ten equals 67,240,000 6.724 x 1092,960,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 Earth141,600,000 9.296 x 10 74.838 x 10 = 8 Jupiter 1.416 x 10 Mars 8 Saturn 890,700,0008 = 483,800,0008.907 x 10 = 483,800,0008.907 x 10 = 483,800,0008.907 x 10 = 483,80 Neptune... 2,793,000,000 Uranus... 1.784 x 109 Triton... 4,900,000,000 Pluto... 3.322 x 1024
These distances are very close to each other, so they can be rounded to the nearest thousandth value: 67,200,000,000. This means that there are about 670 million miles between the Sun and Mercury, almost 70 billion miles between the Sun and Jupiter, nearly 13 trillion miles between Earth and Saturn, about 88 billion miles between Earth and Mars, almost 15 billion miles between Earth and Venus, over 530 billion miles between Earth and Uranus, almost 17 billion miles between Earth and Triton, and more than 30 billion miles between Earth and Pluto.
Including all the planets except Pluto, which is a dwarf planet, the total mass of the Solar System is about two-thirds of Earth's mass. The heaviest object in the Solar System is Jupiter, with mass more than 300 times that of Earth's moon. The lightest object is Pluto, which is only one-quarter as massive as Earth's moon.
The Sun is approximately 400,000 miles wide.
|Planet (or Dwarf Planet)||Distance from the Sun (Astronomical Units miles km)||Mass (kg)|
|Mercury||0.39 AU, 36 million miles 57.9 million km||3.3 x 1023|
|Venus||0.723 AU 67.2 million miles 108.2 million km||4.87 x 1024|
|Earth||1 AU 93 million miles 149.6 million km||5.98 x 1024|
|Mars||1.524 AU 141.6 million miles 227.9 million km||6.42 x 1023|
Mercury is 0.4 astronomical units distant from the Sun at an average distance of 36 million miles (58 million kilometers). The distance between the Sun and Earth is measured in astronomical units (abbreviated as AU). One astronomical unit is the mean distance between the Earth and the Sun, about 150 million miles (241 million km).
Thus, 0.4 AU = 1 astronomical unit.
|Planet (or Dwarf Planet)||Distance from the Sun (Astronomical Units miles km)|
|Earth||1 AU 93 million miles 149.6 million km|
|Mars||1.524 AU 141.6 million miles 227.9 million km|
Mercury must have a higher orbital velocity than Earth since it is nearest to the Sun. This is why Mercury is the planet with the greatest speed in relation to our sun. This is also why, when a planet moves away from the sun, its orbital velocity decreases (as long as the orbit is near circular, if not, circular).
Earth's orbital velocity is about 30 km/s, while that of Mercury is 43 km/s. These numbers show that Mercury travels more than half way across the solar system every single day!
This high velocity is due to two factors: first, Earth's mass is more than 95% hydrogen and helium, whereas Mercury is almost entirely iron; second, both planets are affected by the Sun's gravity, but because of their distances from it, their orbits are not exactly the same shape. If Earth were made of iron instead of carbonate rock, its orbit would be closer to that of Mercury and it would experience far less gravitational force from the Sun than does Mercury.
The fact that Mercury is fast rotating too helps its escape velocity increase even more. On Earth, we experience relatively little centrifugal force because we are so far away from the center of our planet. But because Mercury is so close to the Sun, it experiences very strong centripetal forces which help it maintain this high velocity.
Also, because it is so close to the Sun, all of Mercury's days are equally hot and dark.