Comet 46P/Wirtanen might reach naked eye level by the end of 2018. Comet 46P/Wirtanen is due to pass closest to the sun and the Earth in December. Wirtanen’s closest approach to the sun will be on Dec. 12 and its closest approach to the Earth will be on Dec. 16.
Comet Wirtanen belongs to the Jupiter family of comets. Its orbit is very eccentric, with its closest approach being just outside the Earth’s orbit and its farthest point being just inside Jupiter’s orbit. The comet orbits the sun every 5.4 years. The comet is named after its discoverer, Carl A. Wirtanen, who discovered it on Jan. 17, 1948.
How bright a comet becomes depends on a few factors. These include how close to the Earth the comet comes and how much material is being ejected by the nucleus of the comet. Comet Wirtanen will pass the Earth at about 30 times the moon’s distance (7.1 million miles, or 11.5 million km). This will make the comet the 10th closest approaching comet in modern times.
How bright will the comet get? That’s hard to say. Current estimates suggest that the comet will brighten to between magnitude 3.5 and magnitude 6.0. The lower the magnitude the brighter the object is. Typically, objects lower than magnitude 5.0 are visible in places with dark skies. Comets are usually brightest around their closest approach to the sun. They are also brighter when they are closest to the Earth. This pass of Comet Wirtanen has it being closest to the Earth just three days after its closest approach to the sun. These are the best possible conditions for a bright comet.
The last condition for a bright comet is how much material is being ejected from the comet. As comets come closer to the sun, they brighten. This is caused by the outer layer of the icy crust and the material just below the crust heating up and forming geysers on the comet. The material that shoots off the comet forms its tail and later becomes the material in meteor showers. The greater the amount of material shooting into space, the larger the comet appears and the greater its brightness. At this point, the amount of material seems to be average for this comet.
What will you be able to see? If you have binoculars or a small telescope, you should be able to see a diffuse coma around a small 0.75 mile (1.2 km) wide nucleus. It is possible that the coma will grow to be about the size of the moon in mid-December. Due to the orientation of the comet at closest approach, we will not be able to see the comet’s tail
If you do not have a telescope or binoculars, you can still see the comet. You can see the comet online by going to www.virtualtelescope.eu between Dec. 12 and 17.
For more information on Comet Wirtanen go to http://wirtanen.astro.umd.edu/46P/46P_2018.shtml. For information on the daily location of the comet, go to https://in-the-sky.org/news.php?id=20181216_18_100.
THE NIGHT SKY OVER AROOSTOOK COUNTY
All of the times and events listed below are from www.calsky.com. You may register at this site and load your location (anywhere in the world) to be able to get event information and times. The University of Maine at Presque Isle is located at 68d00m7.8s west longitude and 46d40m45.6s north latitude.
The International Space Station is visible as follows:
Evenings – Nov. 23 to Dec. 15.
Mornings – Dec. 23 to Jan. 16.
To get a free sky chart go to www.skymaps.com.
Sun and Planet Visibility
Not visible Mercury.
03:18 – 06:48 Venus.
16:24 – 23:00 Mars.
Not visible Jupiter.
16:24 – 18:00 Saturn.
05:18 – 06:48 Mercury.
03:18 – 07:06 Venus.
16:18 – 22:54 Mars.
06:12 – 06:48 Jupiter.
16:18 – 17:06 Saturn.
11/17 05:00 Leonid Meteor Shower – 7.3 meteors per hour.
11/17 18:00 Leonid Meteor Shower – 8.0 meteors per hour.
11/18 05:00 Leonid Meteor Shower – 7.4 meteors per hour.
11/23 00:39 Full Moon.
11/23 22:43 Jupiter farthest from the Earth (589,991,000 miles or 949,498,000 km).
11/26 01:33 Jupiter 0.66 degrees from the sun.
11/26 07:20 Moon at Perigee (227,791 miles or 366,594 km).
11/26 18:30 Mercury closest to the Earth (63,024,000 miles or 101,427,000 km).
11/27 03:06 Mercury in conjunction with the sun, 0.9 degree away.
11/27 16:11 Mercury 0.4 degrees from Jupiter.
11/29 03:48 Mercury at Perihelion – closest to the sun (28,584,000 mile or 46,001,000 km).
11/29 05:24 Venus at its brightest in morning sky -4.87 magnitude.
11/29 19:18 Last Quarter Moon.
11/30 16:46 ISS passes 0.4 degrees from Vega (Alpha Lyra).
12/03 07:00 Moon 5.2 degrees from Venus.
12/04 16:33 ISS 0.1 degrees from Capella (Alpha Auriga).
12/05 06:24 Moon 5.2 degrees from Mercury.
12/07 02:20 New Moon.
12/07 09:11 Mars 0.03 degrees from Neptune.
12/08 16:30 Moon 4.4 degrees from Saturn.
12/08 17:51 ISS passes 1.3 degrees from Deneb (Alpha Cygnus).
12/10 15:44 earliest sunset of the year.
12/10 17:44 ISS passes 0.2 degrees from Mars.
12/12 07:30 Moon at apogee – farthest from the Earth (251,787 miles or 405,211 km).
12/12 17:12 Comet 46P/Wirtanen at perihelion – closest to the sun 1.06.
12/12 20:35 to 20:43 Moon eclipses Deneb Algedi (Delta Capricorn).
12/13 02:00 Geminid Meteor Shower – 7.0 meteors per hour.
12/13 16:44 ISS passes 0.9 degrees from the moon.
12/14 02:00 Geminid Meteor Shower – 48 meteors per hour.
12/14 05:00 Geminid Meteor Shower Maximum – 50 meteors per hour.
12/14 22:18 Moon 3.5 degrees from Mars.
12/15 02:00 Geminid Meteor Shower – 10.7 meteors per hour.
12/15 Comet 46P/Wirtanen at its brightest.
12/16 08:06 Comet 46P/Wirtanen closest to the Earth (7,157.597 miles or 11,519,036 km).