Earth's Second Moon


Many people are shocked to learn that there is another moon that is discussed.

Growing up, we all have learned and saw that there is only one Moon in the sky. However, there is an object that is considered as the Earth’s second Moon. It orbits around the sun in approximately 1:1 orbital resonance with the sun. Although it seems like the second Moon, it is not really the second “Moon” because the Earth’s gravity does not affect it and it’s not affected by Earth like the real moon. It is actually a quasi-satellite, known as 3753 Cruithne. It was first discovered by Duncan Waldron on the October 10th 1986, in Australia. Duncan was the person who actually was responsible for locating this quasi-satellite. Its diameter is about 3 miles, the mass is about 130,000,000,000,000kg, and the temperature is about 2 degrees Celsius.

From 1994 to 2015, Cruithne made and will continue making a closest approach to the Earth every November, which is 30 times the distance between the Earth and the Moon. It takes about 770 years for Cruithne to orbit the Earth and takes about 364 days to revolve around the sun. We know that it takes 365 days for the Earth to revolve around the sun. Therefore, eventually, Earth is going to end up following Cruithne because Cruithne becomes quicker than the Earth for revolutions. Therefore, the orbit and the Earth will pull away from each other. The last time Cruithne was seen is 1902 and the next time will be 2292.





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