Mercury actually has no moons. Because Mercury is so close to the sun and its gravity, it could not hold its own moon. Any moon would most likely crash into Mercury or perhaps go into orbit around the Sun and eventually be pulled into it.
Moons — also called natural satellites — come in many shapes, sizes, and types. They are generally solids and few have atmospheres. Most planetary moons likely formed from the disks of gas and dust that circulated around planets in the early Solar System.
There are hundreds of moons in our solar system – even a few asteroids have found small companion moons. Moons beginning with a letter and a year are considered provisional moons. They will be given a proper name when their discoveries are confirmed by additional observations.
Why does Mercury have no moons or rings?
Mercury has no moons. The planet’s close proximity to the Sun makes it impossible to have moons, as the star’s strong gravitational pull would likely pull them out of the planet’s orbit.
Any moon too far from these planets would be in an unstable orbit and be captured by the sun. If they got too close to these planets, they would be destroyed by the gravitational forces of the tides. The zones in which moons might be stable around these planets over billions of years are probably so narrow that none were ever put into orbit or created in situ when the planets were first accreted.
With a radius of 1,516 miles (2,440 kilometers), Mercury is just over 1/3 the width of Earth. If Earth were the size of a nickel, Mercury would be about the size of a blueberry.
At an average distance of 36 million miles (58 million kilometers), Mercury is 0.4 astronomical units from the Sun. An astronomical unit (abbreviated as AU) is the distance from the sun to the earth. From that distance, it takes sunlight 3.2 minutes to travel from the Sun to Mercury.
Mercury’s surface temperatures are both extremely hot and cold. Because the planet is so close to the sun, daytime temperatures can reach highs of 430°C (800°F). Without an atmosphere to retain this heat at night, temperatures can drop as low as -290°F (-180°C).
How many rings does mercury have?
Unfortunately, Mercury could never get such rings. That’s because it’s too close to the sun. The powerful solar winds emanate from the sun and would melt and destroy all ice rings around Mercury. In fact, ice cannot exist closer to the sun than the asteroid belt unless it is hidden in shadow or protected by an atmosphere like we have on Earth.
The second form of ring formation is when an asteroid or moon gets too close to a planet and is torn apart by gravity. For a few million years, this shattered asteroid would appear as a ring around Mercury until the chunks eventually fell to the planet. Astronomers predict that Martian moon Phobos will eventually meet this fate, being torn apart by Mars’ gravity and forming a ring for a while.
Mercury doesn’t have moons and there aren’t many asteroids to interact with, so it might never get a ring — but maybe someday. However, one thing is certain, there are no Mercury rings today.
How long is a day on Mercury?
A planet’s day is the time it takes for the planet to rotate or spin around its axis once. Mercury rotates very slowly compared to Earth, so a day on Mercury lasts much longer than a day on Earth. A day on Mercury is 58.646 Earth days or 1407.5 hours long, while a day on Earth is 23.934 hours long.
Mercury is one of the most unusual planets in our solar system, at least by the standards of us privileged Earthlings. Although it is the planet closest to the Sun, it is not the hottest (that honor goes to Venus). And because of its virtually nonexistent atmosphere and slow rotation, temperatures on its surface range from extremely hot to extremely cold.
Equally unusual is the daily cycle on Mercury – i.e. the cycle of day and night. A single year on Mercury lasts only 88 days, but thanks to its slow rotation, a day lasts twice as long! That means if you could stand on the surface of Mercury, it would take an incredible 176 Earth days for the sun to rise, set, and rise again in the same place in the sky just once!