Second earth moon

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A second earth moon is a hypothetical, in addition to the earth moon existing further natural satellite of the earth, whose past or present existence can be the subject of hypotheses or fiction . Such a device would have to circumnavigate the earth within its hill sphere, i.e. with a maximum distance of about 1,500,000 kilometers (about 4 times the mean earth-moon distance ). In fact, the current existence of such an object can be ruled out from a size of a few meters. This is the result of systematic searches such as those carried out by William Henry Pickering in 1903 .

Observational claims

In the 19th and 20th centuries, some discoveries of a second earth moon were published, but in no case could they be confirmed by astronomical observations.

Petit (1846)

The French astronomer Frédéric Petit (director of the Toulouse observatory at the time ) announced the discovery of a second, extremely small moon in 1846. This should have an orbital time of 2 hours 44 minutes, with an apogee of 3570 km and a perigee of only 11.4 km above the earth's surface. This claim was immediately met with skepticism among specialist colleagues and was rejected. Urbain Le Verrier objected that the air resistance at the perigee altitude mentioned would prevent a permanently stable orbit with these data. However, Petit stuck to his discovery and justified the existence in another publication in 1861 with an allegedly observed influence on the lunar movement.

Waltemath (1898, "Lilith")

Waltemath's announcement of the elements of the second moon on earth

Georg Waltemath from Hamburg attracted attention in 1898 with the alleged discovery of a second earth moon, especially since he claimed that a transit before the sun could be observed for this at short notice . This was then not observed by specialist astronomers, while a number of amateur observers believed they actually saw the transit (they may have observed sunspots ).

In 1918, this claim was taken up by the English astrologer Sepharial (Walter Richard Old), who claimed that this celestial body actually existed and was even similar in size to the moon, but was so dark that it was only in transit in front of the sun or other celestial bodies could be observed. (Such a body is actually not physically possible, since it would have to give off absorbed optical radiation as thermal radiation and could therefore be easily found with today's observation technology in the infrared .) He gave it the name Lilith (after Adam's first wife in the Apocrypha ) and secured it Because of this memorable choice of name, astrology followers are constantly interested in this object. In the 1930s, the French astrologer Dom Néroman (Pierre Rougié) transferred the name "Lilith" to a special point on the lunar orbit, so that the astrological concept could be maintained despite the now obvious non-existence of the celestial body.

Second earth moon in the past

In 2011, some scientists theorized that shortly after its formation, the earth actually had two moons . After a few million years, the smaller of the two moons should have collided with the larger one, which explains the considerable differences between the front and back of the moon . However, a study published in 2019 names the impact of a dwarf planet as the preferred explanation.

Other celestial bodies referred to as the “second earth moon”

Earth orbit cruisers and Trojans

Earth orbit cruisers such as the asteroids 2002 AA29 , 2003 YN 107 and (3753) Cruithne or earth Trojans such as the asteroid 2010 TK 7 are sometimes incorrectly referred to in the non-scientific press as "second earth moons", although they represent the sun (albeit in a similar or same orbital period as the earth) and not orbit the earth. However, in 2003 YN 107 is likely to be captured by the earth in the year 2120 and then actually become a real second earth moon.

Temporary mini satellites

Furthermore, there are asteroids whose orbit is so disturbed when passing close to the earth that they remain close to the earth for a few months or years when they orbit the sun and, when viewed from the earth, orbit it several times. However, they do not take long-term stable orbits around the earth, which they would qualify as ("captured", possibly irregular ) satellites. Such a celestial body "the size of a small car" ( 2006 RH 120 ) was observed, for example, in 2006 and called the "moon", similar to the "mini moon" 2020 CD 3 in 2020 .

Second earth moon in fiction

Jules Verne took up the theory of a second earth moon, possibly inspired by the claims of Frédéric Petit, in his 1870 novel Journey around the moon . Here the spaceship, which is supposed to bring the astronauts from earth to the moon, is deflected by a second, asteroid-sized earth satellite, whereby the spaceship misses the moon and never arrives at it.

The plot of the multi-volume novel 1Q84 by the Japanese writer Haruki Murakami , published in 2009/2010, takes place for the most part in a parallel reality , the hallmark of which is that a second, smaller moon can always be seen in the sky close to the moon.

In the US science fiction film A Rift in the World , a second earth moon is created by escaping magma .

The comic artist Carl Barks had Dagobert Duck compete in the 1958 story "Lost Moon Gold" (original title: The Twenty-four Carat Moon ) in a space race to a newly discovered moon on earth. It is located in the shadow of the well-known moon and is made of pure gold .

See also

Web links

Individual evidence

  1. ^ William Henry Pickering: On a photographic search for a satellite of the Moon . In: Popular Astronomy, 1903
  2. ↑ Patrick Moore . The Wandering Astronomer . CRC Press, 1999, ISBN 0-7503-0693-9 , pp. 137-140, excerpt from Google Books
  3. ↑ a b Paul Schlyter: The 8 Planets - Appendix 7: Hypothetical Planets - Chapter: The Second Earth Moon, 1846-today. www.neunplaneten.de, April 10, 2014, accessed on April 18, 2015 .
  4. ↑ Georg Waltemath: Astronomical Mittheilungen. Appeal to the astronomers and friends of astronomy. A second moon on earth. Hamburg 1898, scan from Wikimedia Commons
  5. ↑ A Stray Moon . In: The Washington Times , August 7, 1898, p. 15. Retrieved August 25, 2013. “It is a real weather and magnet moon, and whenever it is about to cross the earth's course it disturbs the atmosphere and surface of the earth, producing storms, rain, tempests, magnetic deviations and earthquakes ... " 
  6. ↑ a b David Faulks: Proposal to add some Western Astrology Symbols to the UCS. (PDF) In: Unicode Technical Committee Document No. L2 / 06-171. ISO / IEC JTC1 / SC2 / WG2, May 9, 2006, accessed March 8, 2015 .
  7. ^ Martin Jutzi, Erik Asphaug: Forming the lunar farside highlands by accretion of a companion moon . In: Nature . No. 476, August 2011, pp. 69-72. doi : 10.1038 / nature10289 .
  8. ↑ Jan Oliver Löfken: New evidence: Second moon once orbited the earth. weltderphysik.de, August 3, 2011, accessed April 18, 2015 .
  9. ↑ Daniela Albat: Did an impact shape the sides of the moon? - Collision with a dwarf planet could explain asymmetries between the front and back. scinexx , May 21, 2019, accessed May 21, 2019 .
  10. ↑ Distant Companion - Does Earth Have a Second Moon? focus.de, March 3, 2015, accessed on April 18, 2015 .
  11. ↑ Mikael Granvik, Jeremie Vaubaillon, Robert Jedicke: The population of natural Earth satellites . December 16, 2011, doi : 10.1016 / j.icarus.2011.12.003 , arxiv : 1112.3781 .
  12. ↑ Bruce Dorminey: Earth's Come & Go Moons . In: Sky & Telescope, September 2015, pp. 30–33
  13. ↑ Mini moons orbit the earth. Frankfurter Rundschau, March 30, 2012, accessed on April 18, 2015 .
  14. ↑ Earth has probably caught a mini moon. Spektrum.de , February 27, 2020, accessed on February 27, 2020 .