What is the earths second moon called, whats its orbital lenght and when and who discoveer it?

Question

What is the earths second moon called, whats its orbital lenght and when and who discoveer it?

Answer 1

3753 Cruithne

Discovered 10 Oct 1986 by Duncan Waldron

Answer 2

3753 Cruithne

Answer 3

we have a second moon? wow, you learn something new every day, cool :-)

Answer 4

I cant remember it :( google earths second moon then go on the wikipedia page. Technically its not earthes moon coz it orbits the sun not the earth

Answer 5

Your thinking of 3753 Cruithne. Cruithne was discovered on October 10, 1986, by Duncan Waldron and was once thought to have a highly elliptical orbit around the Earth yet later discovery showed that it was in fact orbiting the sun. Its certain orbital path gave the hint that it might orbit the Earth when it was really no more than an illusion. And the question still seems to stand among astronomers... should a non-spherical body still be considered a moon? So if this did orbit the Earth, should it still be considered a moon? There seems to be some debate among it now... separating a "moon" from a "natural satellite". Why can't we go back to the good old days when "moon" and "natural satellite" were one in the same?

Answer 6

Do you mean 3753 Cruithne?

It is more of an asteriod that a moon, it has an orbit about the sun that slightly overlaps our own occasionally bringing it in close proxitimity to us.

It was discovered on Oct 10th 1986  

Answer 7

Discovery

Cruithne was discovered on October 10, 1986, by Duncan Waldron on a photographic plate taken with the UK Schmidt Telescope at Siding Spring Observatory, Coonabarabran, Australia. The 1983 apparition (1983 UH) is credited to Giovanni de Sanctis and Richard M. West of the European Southern Observatory in Chile. It was not until 1997 that its unusual orbit was determined by Paul Wiegert and Kimmo Innanen, working at York University in Toronto, and Seppo Mikkola, working at the University of Turku in Finland.

The asteroid is named after the Cruithne people (also known as the Priteni or the Picts) who inhabited Scotland and parts of Ireland and the Isle of Man between 800 BCE and 1000 CE[citation needed]; the name may specifically refer to their legendary first leader, also called Cruithne.

[edit] Dimensions and orbit

Cruithne and Earth seem to follow each other in their orbits.

Cruithne and Earth seem to follow each other in their orbits.

Cruithne appears to make a bean-shaped orbit from the perspective of Earth.

Cruithne appears to make a bean-shaped orbit from the perspective of Earth.

Cruithne is approximately 5 km in diameter, and its closest approach to Earth is approximately 30 times the separation between Earth and the Moon (12 Gm or million kilometres). Although Cruithne's orbit is not thought to be stable over the long term, calculations by Wiegert and Innanen showed that it has likely been synchronized with Earth's orbit for a long time. There is no danger of a collision with Earth for millions of years, if ever. Its orbital path and Earth's do not cross, and its orbital plane is currently tilted to that of the Earth by 19.8°. Cruithne, having a maximum opposition magnitude of +15.8, is fainter than Pluto and would require at least a 12.5 inch reflecting telescope to be seen.[3][4]

Cruithne is in a normal elliptic orbit around the Sun. However, because its period of revolution around the Sun is almost exactly equal to that of the Earth, they appear to "follow" each other in their paths around the Sun. This is why Cruithne is sometimes called "Earth's second moon".[2]However, it does not orbit the Earth and is not a moon.[5] Cruithne's distance from the Sun and orbital speed vary a lot more than the Earth's, so from the Earth's point of view Cruithne actually follows a kidney bean-shaped horseshoe orbit ahead of the Earth, taking slightly less than one year to complete a circuit of the "bean". Because it takes slightly less than a year, the Earth "falls behind" the bean a little more each year, and so from our point of view, the circuit is not quite closed, but rather like a spiral loop that moves slowly away from the Earth.

After many years, the Earth has fallen behind far enough that Cruithne is now actually "catching up" on the Earth from "behind". When it eventually does catch up, Cruithne will make a series of annual close approaches to the Earth, and gravitationally exchange orbital energy with Earth; this will alter Cruithne's orbit by a little over half a million kilometres (whilst Earth's orbit is altered by about 1.3 centimetres) so that its period of revolution around the Sun is slightly more than a year. The kidney bean then starts to migrate away from the Earth again in the opposite direction — instead of the Earth "falling behind" the bean, the Earth is "pulling away from" the bean. The next such series of close approaches will be centred on the year 2292 — in July of that year, Cruithne will approach Earth to about 12.5 million km.

After 380 to 390 years or so, the kidney-bean-shaped orbit approaches Earth again from the other side, and the Earth, once more, alters the orbit of Cruithne so that its period of revolution around the Sun is again slightly less than a year (this last happened with a series of close approaches centred on 1902, and will next happen with a series centered on 2676). The pattern then repeats itself.

[edit] Similar minor planets

Three other near-Earth asteroids (NEAs), 54509 YORP, (85770) 1998 UP1 and 2002 AA29, which exist in resonant orbits similar to Cruithne's, have since been discovered.

Other examples of natural bodies known to be in horseshoe orbits include Janus and Epimetheus, natural satellites of Saturn. The orbits these two moons follow around Saturn are much simpler than the one Cruithne follows, but operate along the same general principles.

Mars has four known co-orbital asteroids (5261 Eureka, 1999 UJ7, 1998 VF31, and 2007 NS2, all at the LaGrange points), and Jupiter has many (more than 1000 known objects, the Trojan asteroids); there are also other small co-orbital moons in the Saturnian system: Telesto and Calypso with Tethys, and Helene and Polydeuces with Dione. However, none of these follow horseshoe orbits.

Answer 8

The second moon is no longer classed as a moon.

The current thinking is that their are either 1 or 4 moons.

Doesn't anyone watch the recent QI

Answer 9

The Earth's second known satellite was Sputnik.  It was junk discovered in some Russian's basement before it was launched into orbit in 1958.  It's come home to roost now.

3753 Cruithne is an asteroid, not a moon.  But the story is very interesting.  Thanks to the answers that brought it and similar asteroids up.  Very cool.