Other moons of Earth

Claims have existed for many centuries that the Earth might possess more than one Moon. Several have been proposed, though none have ever been verified. While the Moon remains the Earth's only true satellite, a number of objects, such as the quasi-satellite 3753 Cruithne, have been referred to somewhat glibly as "second moons" of Earth^[1], as well as 54509 YORP, (85770) 1998 UP₁, 2002 AA₂₉, 2000 PG₅, 2000 WN₁₀.

While several genuine scientific searches for "second moons" were undertaken in the 19th and 20th centuries, it has also been the subject of several non-scientific proposals and possible hoaxes. These possible hoaxes, which were about objects of specific size and orbits, were poorly founded and were disproven.^[2] However, many near-Earth objects have been discovered including some quasi-satellites.

There have been large generic searches for small moons, actual proposals or claimed sightings of specific objects in orbit, and finally, analysis and searches for those proposed objects. All three of these have not confirmed a permanent natural satellite.

History

The first major claim of a second moon was a report in 1846 by Toulouse Observatory, but further scientific observations and study did not confirm that proposed object. Other specific claims of objects and orbits that suggested to be second moons have also failed to be confirmed.

In recent years the periodic inclusion planetoid 3753 Cruithne (confirmed in 1997) has been given the moniker "Earth's second moon",^[3] which orbits the Sun in an elliptical orbit but appears to have a horseshoe orbit when viewed from Earth.^[1][3]

Past proposals

There have been several cases of people proposing second earth moons, but only one was by a professional astronomer at observatory.

Toulouse Observatory sighting & Petit's moon

In 1846, French astronomer Frédéric Petit, director of the observatory at Toulouse Observatory, France, announced that he had discovered a second moon in an elliptical orbit around the Earth. It was claimed to be reported by Lebon and Dassier also at Toulouse, and Lariviere at Artenac Observatory, during the early evening of March 21, 1846.^[4]. Petit proposed that this second moon had an elliptical orbit, a period of 2 hours 44 minutes, with 3,570 km apogee and 11.4 km perigee. ^[4] This claim was soon dismissed by his peers. ^[5] The 11.4 km perigee is only 37,401 feet altitude, which is closer to Earth than jetliners fly.

Frédéric Petit became obsessed with the 1846 observations and ended up publishing another paper 15 years later, basing the second moon's existence on perturbations in movements of the existing moon. ^[4] This second moon hypothesis was not confirmed, either; however, the concept was taken up by science fiction writer Jules Verne, who included a fictional moon based on Petit's second proposal for a second moon in From the Earth to the Moon.^[4] This fictional moon, however was not exactly based on the Toulouse observations or Petit's proposal at a technical level, and so the orbit suggested by Verne was mathematically incorrect. ^[4] Unfortunately, Frédéric Petit died in 1865, and so was not alive to offer a response to Verne's fictional moon^[6].

Waltemath's moons

Dr. Georg Waltemath searched for secondary moons based on the hypothesis that something was affecting the Moon's orbit.^[8] In 1898, Hamburg scientist Dr. Georg Waltemath announced he had located a second moon^[9] inside a system of tiny moons orbiting the Earth.^[10] Waltemeth is reported as saying, "Sometimes, it shines at night like the sun but only for an hour or so"^[11], later quoted by the The Cambridge Planetary Handbook.^[12]

Waltemath gave the description of one of the proposed moons as being 1.03 million km from earth (640,000 miles), with a diameter of 700 km (435 miles), an orbital period 119 days, and a synodic period 177 days.^[4] He also said it did not reflect enough sunlight to be observed without a telescope, unless viewed at certain times, and made several predictions as to when it would appear.^[13] However, after the failure of a corroborating observation of Waltemath's moons by the scientific community, these objects were discredited. Especially problematic was a failed prediction that they would be observable in February 1898 ^[4] Waltemath proposed more moons, according to a mention in August 1898 issue of Science. The third moon was closer then the first, 746 km in diameter, and he called it "Warhafter Wetter-und Magnet Mond". ^[7]

In 1918, astrologer Walter Gornold, also known as Sepharial, claimed to have confirmed the existence of Waltemath's moon. He named it Lilith. Sepharial claimed that Lilith was a 'dark' moon invisible for most of the time but claimed to have viewed it as it crossed the sun.^[14]

1900s

In 1926, the science journal Die Sterne published the findings of an amateur German astronomer named W. Spill, who claimed to have successfully viewed a second moon orbiting the earth.^[12]

In the late 1960s John Bargby claimed to have observed over ten small natural satellites of the Earth, but this was not confirmed.^[4]

General surveys

William Henry Pickering (1858-1938), studied the possibility of a second moon and made general search ruling out the possibility of many types of objects by 1903.^[15] Many years later his article "A Meteoritic Satellite" in Popular Astronomy in 1922 resulted in increased searches for small natural satellites by amateur astronomers. ^[4] Pickering had also proposed the Moon itself had broken off from earth.^[16]

Clyde Tombaugh, the discover of the (then called) planet Pluto, was sponsored by the United States Army Office of Ordnance Research to do a search for near earth asteroids. Another public statement was made on the search in March 1954, emphasizing the rationales for the search.^[17] However, according to Donald Keyhoe, later director of the National Investigations Committee on Aerial Phenomena (NICAP), the real reason for the sudden search was because two near-Earth orbiting objects had been picked up on new long-range radar in mid-1953, according to his Pentagon source. By May 1954, Keyhoe made public statements that his sources told him the search had indeed been successful, and either one or two objects had been found.^[18] However, the story did not really break until August 23, 1954, when Aviation Week magazine stated that two natural satellites had been found only 400 and 600 miles (970 km) out. However, both LaPaz and Tombaugh were to issue public denials that anything had been found. The October 1955 issue of Popular Mechanics magazine reported:

"Professor Tombaugh is closemouthed about his results. He won't say whether or not any small natural satellites have been discovered. He does say, however, that newspaper reports of 18 months ago announcing the discovery of natural satellites at 400 and 600 miles out are not correct. He adds that there is no connection between the search program and the reports of so-called flying saucers."^[19]

At a meteor conference in Los Angeles in 1957, Tombaugh reiterated that his four year search for "natural satellites" had been unsuccessful.^[20] In 1959, Tombaugh was to issue a final report stating that nothing had been found in his search.

Although a second natural satellite of the Earth does not exist, there are various types of Near-Earth object in quasi-orbits. Examples of such objects include 2006 RH120 or 3753 Cruithne.

Earth's "second moon" in literature

Petit's second moon was not accepted, but he continued to search explanations resulting another proposal 15 years later. ^[4] The writer Jules Verne learned of Petit's second proposals for a second moon theory. He became intrigued by the idea and made use of it in his 1865 novel, From the Earth to the Moon. ^[5] The explosive popularity of Jule's Verne's book in the 19th century triggered many amateur astronomers to search for second moons around earth although Petit did not live to see this, having passed away in 1865. Samuel R. Delany's 1975 novel Dhalgren features an Earth which mysteriously acquires a second moon. Eleanor Cameron's Mushroom Planet novels for children (the first being The Wonderful Flight to the Mushroom Planet) are set on a tiny, habitable second moon called Basidium in an invisible orbit 50,000 miles (80,000 km) from Earth.

References

See also

• List of hypothetical Solar System objects
• Lost asteroids, rediscovered celestial bodies
• Lagrange points
• Lilith (hypothetical moon), second earth moon in astrology
• Quasi-satellite
• Near-Earth objects
• Counter-Earth

External links

• Earth’s Other Moon
• The Earth's Second Moon, 1846-present
• A detailed explanation of secondary moon theories
• Have astronomers discovered Earth's second moon?
• Near-Earth asteroid 3753 Cruithne --Earth's curious companion--

Further reading

• Public Opinion: A Comprehensive Summary of the Press Throughout the World on All Important Current Topics

Published by Public Opinion Co., 1898, Page 369. Book

• Research paper describing horseshoe orbits.

• Willy Ley: "Watchers of the Skies", The Viking Press NY,1963,1966,1969
• Carl Sagan, Ann Druyan: "Comet", Michael Joseph Ltd, 1985, ISBN 0-7181-2631-9
• Tom van Flandern: "Dark Matter, Missing Planets & New Comets. Paradoxes resolved, origins illuminated", North Atlantic Books 1993, ISBN 1-55643-155-4
• Joseph Ashbrook: "The Many Moons of Dr Waltemath", Sky and Telescope, Vol 28, Oct 1964, p 218, also on page 97-99 of "The Astronomical Scrapbook" by Joseph Ashbrook, Sky Publ. Corp. 1984, ISBN 0-933346-24-7
• Delphine Jay: "The Lilith Ephemeris", American Federation of Astrologers 1983, ISBN 0-86690-255-4
• William R. Corliss: "Mysterious Universe: A handbook of astronomical anomalies", Sourcebook Project 1979, ISBN 0-915554-05-4, p 146-157 "Other moons of the Earth", p 500-526 "Enigmatic objects"
• Clyde Tombaugh: Discoverer of Planet Pluto, David H. Levy, Sky Publishing Corporation, March 2006
• Richard Baum & William Sheehan: "In Search of Planet Vulcan" Plenum Press, New York, 1997 ISBN 0-306-45567-6 , QB605.2.B38