C / 2021 A1 (Leonard)

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C / 2021 A1 (Leonard) [i]
C / 2021 A1 (Leonard) on November 28, 2021
C / 2021 A1 (Leonard) on November 28, 2021
Properties of the orbit ( animation )
Orbit type hyperbolic
Numerical eccentricity 1,000
Perihelion 0.615 AU
Inclination of the plane of the orbit 132.686 °
Perihelion January 3, 2022
story
Explorer Gregory J. Leonard
Date of discovery January 3, 2021
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 2021 A1 (Leonard) is a retrograde comet that formed on January 3, 2021 (exactly one year to the day before its calculated closest approach to the Sun ) by Gregory J. Leonard at the Mount Lemmon Observatory near Tucson , US state Arizona was discovered. At this point, C / 2021 A1 was about 5 AU from the Sun , roughly as far as Jupiter's orbit. It is the first comet to be discovered in 2021.

On December 12, 2021, it will approach Earth to within 0.23 AU (approx. 34.4 million km) , and on December 18, 2021 to within 0.028 AU (approx. 4.2 million km) Venus . On January 3, 2022, it will reach perihelion, about 0.62 AU from the Sun. On October 10, a short but dense dust trail was observed on the comet . It is expected that C / 2021 A1 will reach an apparent magnitude of 4 mag during the course of December 2021 . Then it would be visible with the naked eye in the night sky and could be easily observed with binoculars.

On the morning of December 6, 2021, C / 2021 A1 should be about 5 ° away from Arctur in the sky. Around December 14, 2021, it will then be 14.7 ° away from the sun and will then be increasingly easier to observe from the southern hemisphere. Due to scattering effects, the comet could then achieve a brightness of up to 1 mag.

On its orbit around the sun, the comet's nucleus entered the orbit of Neptune in mid-2009 , albeit at a very steep angle from above the orbital plane of the planets. Its orbital period is calculated to be around 80,000 years, the furthest distance to the sun at around 3,700 AU - 75 times as far as the orbit of Pluto (Aphelion 49.3 AU). It is assumed that after passing through its perihelion, C / 2021 A1 swings into a hyperbolic orbit and is thus thrown out of the solar system.

Individual evidence

  1. ↑ CBET 4907: original 1 / a = +0.000575 (long-period) and future 1 / a = -0.000030 (hyperbolic). The orbital energy is inversely proportional to the negative semi-major axis. Objects in hyperbolic orbits have negative semi major axis, giving them a positive orbital energy.
  2. ↑ MPEC 2021-A99: COMET C / 2021 A1 (Leonard) . Minor Planet Center. Retrieved January 10, 2021.
  3. ↑ PL Small-Body Database Browser: C / 2021 A1 . JPL. Retrieved September 29, 2021.
  4. ↑ How Bright Will Comet Get Leonard? ( en-US ) In: Sky & Telescope . October 13, 2021. Retrieved October 20, 2021.
  5. ^ Prediction of the brightness of C / 2021 A1 - TheSkyLive.com
  6. ↑ Horizons output: Solar elongation Comet C / 2021 A1 (Leonard) in mid-December 2021 . Retrieved October 17, 2021. Sun Observer Target (SOT)
  7. ↑ C / 2021 A1 (Leonard) . Gideon van Buitenen. Retrieved November 16, 2021.
  8. ↑ Neptune has perihelion (closest approach to the Sun) at 29.8 AU. C / 2021 A1 has been inside that distance since May 2009.
  9. ↑ JPL Horizons On-Line Ephemeris System output: Barycentric Osculating Orbital Elements for Comet C / 2021 A1 (Leonard) . Retrieved January 13, 2021. (Solution using the Solar System's barycenter (Sun + Jupiter). Select Ephemeris Type: Elements and Center: @ 0) Epoch 1950 has PR = 2.91E + 07 / 365.25 = 79700 years
  10. ↑ JPL Horizons On-Line Ephemeris System output: Barycentric Osculating Orbital Elements for Comet C / 2021 A1 (Leonard) . Retrieved January 13, 2021. (Solution using the Solar System's barycenter (Sun + Jupiter). Select Ephemeris Type: Elements and Center: @ 0) Epoch 1950 has PR = 2.91E + 07 / 365.25 = 79700 years