Comet 46P/Wirtanen next perihelion 2024-May-19

Comet 46P/Wirtanen is an icy small Solar System body that, when passing close to the Sun, will warm and begin to release gases, a process called outgassing. This produces a visible atmosphere or coma, and also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. However, this time around, the ion tail will be pointing  away from the Earth and difficult to see due to the geometry. It will hopefully improve as the comet approaches perihelion (19 May 2024).

The Comet 46P/Wirtanen nucleus is approximately 1.2 kilometers diameter (example distance & size shown above) and is composed of loose collections of ice, dust, and small rocky particles. Although actual sizes are yet to be determined, the coma may be up to 15 times the Earth's diameter, while the tail may stretch one astronomical unit. Expected to be sufficiently bright, Comet 46P Wirtanen  may be seen from the Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures.

Comet 46P/Wirtanen was discovered on Jan 17, 1948 by Carl Wirtanen at the Lick Observatory.

The perihelion is the point in the orbit of a planet, asteroid or comet that is nearest to the sun. It is the opposite of aphelion, which is the point farthest from the sun. The perigee is the point in the orbit that is nearest to the Earth, opposite of apogee. 

Comet 46P/Wirtanen is a short period comet with a current orbital period of 1,982 days (5.4 years)

These are the approximate dates of Comet 46P/Wirtanen perihelion since it's discovery: 

• Dec 12, 2018
• Jul 9, 2013
• Feb 4, 2008
• Sep 1, 2002
• Mar 29, 1997
• Oct 25, 1991
• May 22, 1986
• Dec. 17, 1980
• Jul 15, 1975
• Feb 9, 1970
• Sep 6, 1964
• Apr 4, 1959
• Oct 30, 1953
• Apr 30, 1948

46P/Wirtanen belongs to a small family of comets that boast a higher level of activity than expected for their nucleus size. They emit more water vapour than they should. This is one of the reasons for added interest in this regular visitor to the proximity of Earth’s orbit. 

This year the perigee of Comet 46P/Wirtanen occurs Dec 16, 2018 less than 4 days after perihelion.  This is when the comet is near its brightest.  At its closest, the distance from Earth to Comet 46P/Wirtanen will be: 

• 0.0781 AU (1 Astronomical Unit = roughly the distance from the Earth to the sun.)
• 30 Lunar distances
• 11.5 million km
• 7.1 million miles

UPDATE November 18 at 4:26 AM: 

Averted vision is a technique for viewing faint objects which uses peripheral vision. It involves not looking directly at the object, but looking a little off to the side, while continuing to concentrate on the object.