Preview: Comet 45P/Honda–Mrkos–Pajdušáková Brightens in December

Looking for a good binocular comet? Well, if luck is on our side, we should be getting our first looks at periodic Comet 45P/Honda-Mrkos-Pajdušáková as it tops +10th magnitude in dusk skies over the next few weeks. 

Comet 45P/Honda-Mrkos-Pajdušáková is expected to reach maximum brightness around late February 2017. Discovered independently by astronomers Minoru Honda, Antonin Mrkos and L’udmila Pajdušáková on December 3^rd, 1948, Comet 45P/Honda-Mrkos-Pajdušáková orbits the Sun once every 5.25 years on a short period orbit. Comet 45P/Honda-Mrkos-Pajdušáková is set to break binocular +10^th magnitude brightness in mid-December 2017, and may reach a maximum brightness of magnitude +7 from January through February 2017.

Currently and through the end of 2016, the comet sits towards the center of the Milky Way Galaxy in Sagittarius at a faint +15^th magnitude in the evening sky. The comet may break +10^th magnitude and become very briefly visible in the first few weeks of December before getting too close to the Sun to observe in late 2016 and crossing into the morning sky in early 2017.

Visibility prospects: At its brightest, Comet 45P/Honda-Mrkos-Pajdušáková will be passing through the constellation Hercules during closest approach on February 11^th. The comet then passes through the constellations of Corona Borealis, Boötes, Canes Venatici, Ursa Major into Leo through to the end of February as it recedes. In the second week of February, the comet is visible in the dawn sky 82 degrees west of the Sun at maximum brightness. This apparition favors the northern hemisphere. The comet will reach perihelion on December 29^th, 2016 at 0.53 Astronomical Units (AU) from the Sun, and the comet passes just 0.08 AU (7.4 million miles) from the Earth on February 11^th at 14:44 UT. The comet made a slightly closer pass in 2011, and was a fine binocular object that time around. At its closest, the comet will cross nine degrees of sky from one night to the next. Some notable dates for comet 45P/Honda-Mrkos-Pajdušáková are:

November 23^rd: Venus passes 6′ from the comet.

December 12^th: May break 10^th magnitude.

December 14^th: Passes near M75.

December 15^th: Crosses into the constellation Capricornus.

January 4^th: Passes near the +4^th magnitude star Theta Capricorni

January 10^th: Crosses the ecliptic northward.

January 16^th: Passes into Aquarius.

January 22^nd: Passes near NGC 7009, M72 and M73.

January 25^th: Passes 8 degrees from the Sun and into the dawn sky.

January 28^th: Crosses into Aquila.

February 3^rd: Crosses the celestial equator northward.

February 4^th: Passes 4′ from the star +3.3 magnitude star Delta Aquilae.

February 6^th: Crosses the Galactic equator.

February 7^th: Crosses into Ophiuchus.

February 9^th: Crosses into Hercules.

February 16^th: makes a wide pass near M3.

February 19^th: Drops back below +10^th magnitude.

This is the final close (less than 0.1 AU) passage of Comet 45P/Honda-Mrkos-Pajdušáková near the Earth for this century.

On July 1^st 1770, Comet D/1770 L1 Lexell passed 0.0151AU from the Earth; a comet in 1491 may have passed closer. Next year’s passage of 45P/Honda-Mrkos-Pajdušáková ranks as the 21^st closest passage of a comet near the Earth.

Why do comets end up with such cumbersome names? Well, comets derive their names from the first three discovers that submit the find within a 24 hour period to the Minor Planet Center’s Central Bereau for Astronomical Telegrams, which, in fact, received its last ‘telegram’ during the discovery of Comet Hale-Bopp around two decades ago. Increasingly, comets are receiving names of all sky surveys such as LINEAR and PanSTARRS from robotic competition against amateur hunters. It does seem like you need an umlaut or the chemical symbol for boron to in your moniker to qualify these days… rare is the ‘Comet Smith.’ But hey, it’s still fun to watch science journalists try and spell the Icelandic volcano Eyjafjallajökull and comet Churyumov-Gerasimenko over and over… Perhaps, we should insist that our first comet discovery is actually spelled Comet Dîckînsðn…

And Comet 45/P is just one of the fine binocular comets on deck for 2017. We’re also expecting Comet 41P/Tuttle-Giacobini-Kresák, 2/P Encke, C/2015 ER61 PanSTARRS Comet C/2015 V2 Johnson to break +10^th magnitude next year… and the next great naked eye ‘Comet of the Century’ could light up the skies at any time.

Binoculars are the best tool to observe bright comets, as they allow you to simply sweep the star field and admire the full beauty of a comet, coma, tail(s) and all. Keep in mind, a comet will often appear visually fainter than its quoted brightness… this is because, like nebulae, that intrinsic magnitude is ‘smeared out’ over an extended area. To my eye, a binocular comet often looks like a fuzzy, unresolved globular cluster that stubbornly refuses to snap into focus.

Don’t miss your first looks at Comet 45/P 45P/Honda-Mrkos-Pajdušáková, as it spans 2016 into 2017.