Mercury is little more than one-third the size of Earth, with a diameter of 3,032 miles (4,879 km). Mercury is around the size of a golf ball if Earth were the size of a baseball. It has a mass about 1/10 that of Earth.
Like Earth, Mercury has a magnetic field, but it is very weak. The magnetic field of Mercury can only protect its atmosphere from harmful particles from outside its solar system. It cannot save its inhabitants from physical harm!
Earth's magnetic field is generated by its iron core, which is also responsible for most of Earth's rotation. However, because Mercury has no iron core, it cannot generate its own magnetic field and instead relies on the Sun to provide all of its energy needs. This means that Mercury is always facing us with its nightside up!
It is estimated that there is water under its crust, so even though Mercury is burning fuel day and night, it still receives enough energy from the Sun to keep its surface warm. If it weren't for this heat, the planet would freeze over in as little as 12 hours!
The average temperature on Mercury is 450 degrees Fahrenheit (232 degrees Celsius), much higher than any other planet except Venus.
Mercury weighs 3.3 x 1023 kilos. This mass is stored in 14.6 billion cubic miles of space (60.8 billion cubic km). Mercury's mass and volume are just around 0.055 times that of the Earth. Only Earth has a higher density.
The Earth averages 12,924 miles or 19,840 kilometers across. Water makes up 70% of its mass. The remaining 30% is made up of land masses including Antarctica.
Mercury has a diameter of 495 miles or 800 kilometers. It has a mass about three-quarters of the size of the Earth.
It orbits the Sun every 88 days. At an average distance of approximately 50 million miles, it is the closest planet to the Sun.
Venus is the second planet from the Sun. It has one of the most hostile environments in the Solar System. The air is 96% carbon dioxide. There is no surface water nor life as we know it.
Earth is the third planet from the Sun. It is the only planet in the Solar System that can support life as we know it. It has an atmosphere composed mainly of oxygen (20%) with small amounts of nitrogen and other gases. There is no solid surface except for the Earth's moon.
Titan is the largest moon in our solar system.
Mercury has a volume of 6.1 x 1010 km3, which is equal to 5.4 percent of the volume of the Earth. In other words, you could fit Mercury inside the Earth 18 times and still have some space left over. Mercury and the Earth's orbits are most likely diametrically opposed. This means that they don't pass directly overhead of each other like the Moon and Earth do, but instead travel in opposite directions around the Sun.
This arrangement keeps both planets from being overtaken by their star. The only real problem with this situation is that it tends to put a strain on any potential friendships between these two planets. If one planet is too far away for direct communication with another, then how do they ever really get to know each other?
It turns out that both planets were originally part of the same dwarf galaxy that was later torn apart by the gravitational force of the Milky Way Galaxy. The remains of this destroyed world now forms the asteroid belt between Mars and Jupiter.
After the creation of Earth, another planet named Venus was also formed from the same material as Earth. But because Venus started its life with an atmosphere almost 100 times thicker than Earth's, it quickly lost this battle for survival. Today, Venus is hot enough to melt lead. There is no water, nor anything else that could potentially support life as we know it.
Mercury is 1.04 AU from the Earth. The researchers calculated that the average distance between two entities travelling in concentric circles in the same plane is precisely proportional to the radius of the inner orbit. They called this distance an "effective radius".
They found that for planets with nearly circular orbits, the effective radius is about one-quarter of the orbital radius. For more elliptical orbits, the effective radius will be a fraction of the semi-major axis, which is the distance between the centers of the two orbits.
Thus the effective radius of Mercury's orbit is 37,000 miles, or 59,528 km. Its mass can then be determined from Kepler's third law: 2πr3/T2 = constant, where r is the effective radius and T is the period of Mercury.