10 October

1986: On 10 October 1986, another object, apart from the Moon and manmade satellites, was discovered in orbit around Earth.

Asteroid 3753 was found by J.D. Waldron and named 'Cruithne' after Celtic tribes who came to Britain between about 880 and 500 BC. It is pulled alternately by the Sun and Earth. When viewed from Earth, its 770-year orbit appears to be horseshoe shaped, but this is an effect of viewing an orbit from a rotating planet.

It actually passes closer to Earth than the Moon. At its closest approach it gets to within about 15 million kilometres of our planet. Its diameter ranges between 2.9 and 6.4 kilometres.

1846: On 10 October 1846, Neptune's moon Triton was discovered by William Lassell while he was observing the newly discovered planet Neptune. He was attempting to confirm his observation of the previous week, that Neptune had a ring. Instead he discovered that Neptune had a satellite, Triton. Lassell soon proved that the ring he thought he had seen was a product of his new telescope's distortion.