The night sky in February 2021

posted 29 Jan 2021, 05:55 by Pete Collins   [ updated 30 Jan 2021, 06:06 ]
by Anne Holt

Sunrise       1st:  07.53          28th:   06.58
Sunset        1st:  16.52          28th:   17.45

Day length  1st:  8hr 58' 25"   28th:  10hr 46' 27"
 
New Moon:  11th at 19.08       Full Moon:  27th at 08.20  (angular diameter 32' 13")

Lunar perigee:  3rd at 19.34  (370126km)
The furthest perigee of the year.  On this night the Moon will be 60% waning and have an angular diameter of 32' 16".

Lunar apogee:  18th at 10.23   (404465km)
37% waxing, angular diameter 29' 31"

The most common name for February's full Moon is the Snow Moon but, to those who used that name in January, it's the Hunger Moon.  Other names are the Celtic Ice Moon, the Chinese Budding Moon, the Medieval English Storm Moon and the Pagan Quickening Moon.
There are many Indigenous American names, one site lists 25 different ones used by various tribes.  Among these are the Arapho Frost Sparkling in the Sun Moon, the Cherokee Bone (or Bony) Moon, the Choctaw Moon of Winds, the Hopi Moon of Purification & Renewal and the Wishram Shoulder to Shoulder around the Fire Moon.  The Sioux called it the Dark Red Calves Moon, though whether this referred to young animals or cold legs isn't specified.
It's also the Lenten Moon. This is defined as either the last full Moon of the winter season or the third full Moon in winter.  As this winter has 3 full Moons it qualifies either way.

Highlights

Nothing which really deserves the name this month.  The beautiful dark clear skies of winter are likely to be covered in cloud and those of us who live in very light polluted towns and cities can't go further afield to observe them, even if they aren't.  However, if you can get away from street lights, the area of the Winter Hexagon can be spectacular when seen through binoculars.

Mars is still visible, high in the evening sky, despite being much fainter now.

We still have plenty of astro darkness - a couple of minutes short of 11 hours on 1st, 9hrs 19 minutes on 28th.  For anyone who doesn't know, astronomical darkness is when the Sun is more than 18 degrees below the horizon.  Astro twilight is when it's between 12 and 18 degrees, nautical twilight is 6 to 12 degrees and civil twilight is the period just after sunset, when it is less than 6 degrees below.

Constellations

Orion
and Taurus are now above the horizon as the sky darkens but start to set at around 2am at the start of February and soon after midnight by the end of the month. Gemini and Auriga are still prominent, remaining above the horizon until the early hours. Leo, the signpost constellation of Spring, is now high in the sky for most of the night and Bootes, with it's bright red star Arcturus is rising soon after 11, and around 9pm at month end. In the early part of the evening the Plough is low in the North East standing on its 'handle', and Cassiopeia high in the North West as darkness falls. By month end, the Summer Triangle will have risen soon after 3am - summer already?  Someone better tell the weather.

Planets

Mercury:  in Capricorn, mag 1.1
Appears very close to the Sun in early February.  On 1st it is only 4 degrees above the horizon at dusk, setting at 18.18, just under 90 minutes after sunset.  It fades rapidly as its apparent separation from the Sun decreases, on 8th when it moves into Aquarius, it is at inferior solar conjunction, down to mag 5.1 and passing 3 degrees 37' north of the Sun.  It begins to brighten again as it moves away and more of the illuminated side faces us. On 18th it goes back into Capricorn and the following day, now at mag 0.9, reaches its highest point in the morning sky - but still only on the horizon as dawn breaks, reaching 6 degrees in the SE by sunrise.  On 28th, brighter at mag 0.2, it rises at 06.05 but only gets to 1 degree by dawn.  On this day it appears only 3 degrees from Jupiter, which rises at 06.21.
WARNING:  Do not attempt to spot the planets through binoculars on this day, the Sun rises at 06.58 and it is all too easy to lose track of time and accidentally catch the first rays.

Venus: in Sagittarius, mag -3.9
Appears very close to the Sun this month, so hardly visible.  It might possibly be spotted on 1st, by observers with a flat, clear SE horizon, it rises at 07.27, less than half an hour before sunrise, and only gets to half a degree above the horizon before the Sun rises about 10 minutes later.
Again, DO NOT attempt to  find it using binoculars. 
It is at aphelion, the furthest point in its orbit from the Sun, on 20th, when it is at a distance of 0.73AU, but rises only a few minutes before it. On 24th, when it moves into Aquarius, the separation is only 7 degrees, down to 6 degrees on 28th, when they both rise at 06.58.

Mars:  in Aries, mag 0.4
Now well past its best but still obviously pink in the evening sky. On 1st it culminates at 17.59 in nautical twilight,  but should be visible 58 degrees above the southern horizon.  Soon after midnight it will have sunk to 10 degrees in the west, setting at 01.43.  On the night of 18th/19th the waxing 41% Moon is 3 degrees 41' south of the planet at 22.45.  They move together over the next couple of hours but are very low in the sky and at their closest after the Moon has set.  Mars moves into Taurus on 24th, slightly fainter at mag 0.8 and visible from around 18.20, an hour after culminating but still high, 55 degrees in the south.  During the month it has been moving towards the Pleiades, on 27th it is 3 degrees 48' SE of the centre of the cluster, 3 degrees 25' to the south on 28th, when it becomes visible around 18.30, at 54 degrees in the SW and remaining reasonably high until midnight, setting at 01.27.

Jupiter:  in Capricorn, mag -1.9
Appears too close to the Sun to be seen for most of February.   On 1st, it rises at the same time as the Sun, apparent separation only 2 degrees. Its position only improves very slightly during the month, on 28th, slightly brighter at -2.0, it rises at 06.21 but is only 1 degree above the horizon as the sky begins to brighten.

Saturn:  in Capricorn, mag 0.6
Close to Mercury and Jupiter in the morning sky but, like the other two, too low to be visible.  On 1st it rises at 07.41 and appears only 7 degrees from the Sun. On 28th, at mag 0.7, it rises at 06.03, just under an hour before sunrise but still fails to clear the horizon by dawn.

Uranus:  in Aries, mag 5.8
Still high in the evening sky.  On 1st it is at 49 degrees in the south when it becomes visible soon after 18.00, and remains reasonably high until 22.30, setting at 01.01. On 17th the 31% Moon is 3 degrees 12' south of the planet, as it becomes visible around 18.45 - another good chance to locate it using binoculars - weather permitting!  On 28th it is 35 degrees in the SW as the sky darkens soon after 19.00, high until around 20.45 and setting at 23.15.   As always, a really dark sky and really good eyesight are necessary for it to be seen without optical aid but it should be easily visible in 10 x 50 binoculars, though a telescope is needed in order to see its greenish blue disc.

Neptune:  in Aquarius, mag 7.9
Now too low in the evening sky for telescopic observation.  On 1st it is only 16 degrees above the horizon at dusk, setting at 20.18.  By mid month it is down to 6 degrees at dusk and on 28th is only 10 degrees from the Sun, setting at 18.37.

Dwarf Planets

Ceres:  in Aquarius, mag 9.4
The smallest of the 5 currently designated dwarf planets is the closest to the Sun, orbiting in the Asteroid Belt between Mars and Jupiter.  It was first seen on Jan 1st 1801, the first object in that region to be found and was thought to be a planet, albeit a very small one - about one fifth the size of Mercury.   It was reclassified as an asteroid in 1805, when the new category was introduced after the discovery of many more objects in that region.  It's the largest body in the Asteroid Belt, having 25% of its total mass, and the only one with enough gravity to have pulled itself into a rounded shape.  Because of this it satisfied the criteria for the new category of dwarf planet, introduced in 2006, and was reclassified as such.
It orbits the Sun in 4.8 years so appears to move around the sky quite quickly, however it isn't at its best this month, very low in the sky at dusk.  On 1st it is only 14 degrees above the horizon, setting at 20.12.  It moves into Cetus on 10th, when it is only at 10 degrees when the sky darkens.  It is in Pisces the last couple of days in February, on 28th it is down to 3 degrees at dusk, setting at 19.27.

Pluto:  in Sagittarius, mag 15.0
Found on Feb 18th 1930 by Clyde Tombaugh, studying photographs taken in January of that year, when it was high in the sky, in the constellation Gemini.  Like Ceres it was first classified as a planet and remained as such until 2006, when the category dwarf planet was introduced, following the discovery of many more small bodies orbiting beyond Neptune.  It takes around 250 years to go round the Sun, so has only completed a little over one third of an orbit since it was first seen.  It is currently very low in the sky, too low for succesful imaging, and won't be high enough from our northern latitude until August 2071, when it will reach 22 degrees in the south for a short time.  This month it appears very close to the Sun, following conjunction in January.

Haumea:  in Bootes, mag 17.4
The third largest object in the Kuiper Belt but, along with Makemake, not found until after many of the much fainter trans Neptunian bodies, because its orbit is highly inclined to the ecliptic (28 degrees) so it was outside the area where searches were concentrated.  There is some controversy about its discovery, Mike Brown's Caltech team at Mount Palomar found it in 2004, but a Spanish team later said that they had seen it in March 2003.  However, they were known to have had access to the Caltech team's data and it has been suggested that they may have gone back to their earlier images when they knew where to look.
Haumea spins very rapidly on its axis, a 'day' lasts just under 4 hours, thought to be the result of a collision early in its history.  This fast spin has caused it to flatten so much at the poles that it is an ellipsoidal shape - its equatorial diameter is about twice the polar diameter.
This month it is high enough in the post midnight sky for experienced astrophotographers to have a go at imaging it, though it will never appear as anything other than a faint dot which moves very slightly over the course of a few days.  On 1st it reaches 21 degrees in the east by 1am and culminates, 55 degrees in the south, at 05.51, and isn't much lower when the sky begins to brighten half an hour later.  By 28th it is at 21 degrees soon after 23.00, culminating, 52 degrees in the south, around 4am and down to 48 degrees in the SW by dawn.

Makemake:  in Coma Berenices, mag 17.2
The second brightest KBO was found in March 2005, this time an undisputed discovery by Mike Brown and his team.  Like Haumea its orbit is highly inclined to the plane of the solar system so it wasn't found until the search was widened away from the ecliptic.
It is also currently high in the sky in the latter part of the night, on 1st it gets to 21 degrees in the east by 23.00 and culminates at 04.38 when it reaches 59 degrees in the south.  It is still high, 53 degrees, when the sky begins to brighten shortly before 06.30.  On 28th it is at 21 degrees in the east soon after 21.00 and culminates at 02.51, still at 59 degrees, then sinking to 46 degrees in the SW by dawn.

Eris:  in Cetus, mag 18.8
The faintest and furthest of the 5 currently designated dwarf planets, discovered on Jan 5th, 2005, again by Mike Brown and his team, from images taken in October 2003.  It is slightly smaller, but 25% more massive, than Pluto.  It takes 557 years to orbit the Sun - it was in Cetus when it was found and will remain within its boundaries until April 2035 when it moves into Pisces.  It has a very elliptical orbit, 38 AU from the Sun at its closest and 97.5 AU at its furthest, so it is considered to be not a KBO but part of the Scattered Disc - a region beyond the Kuiper Belt, which extends further above and below the plane of the Solar System.
This month it is quite high in the sky in the early part of the night, on 1st it is 32 degrees in the south at 18.15, not long before the start of astro darkness, having culminated soon after sunset.  It remains reasonably high for a couple of hours and sets at 23.00.  On 28th it is only 23 degrees in the SW as the sky darkens, and is high enough for imaging for a very short time, setting at 21.46.

Asteroids

A couple of asteroids, which should be visible through amateur scopes, are at opposition this month.

18 Melpomene:  in Cancer, mag 9.4
At opposition on 2nd, when it is higher than 21 degrees for most of the night, culminating at 00.24, when it is 48 degrees above the southern horizon.  By 28th it will have faded to mag 10.1 and culminates at 22.11, slightly higher at 51 degrees.

29 Amphitrite:  in Leo, mag 9.7
Again, high for most of the night.  On 1st it culminates at 02.12, when it is at 42 degrees in the south.  It reaches opposition on 22nd, at mag 9.2, culminating at 00.31, now at 50 degrees.  On 28th it will be at mag 9.3 and get to 50 degrees at 23.57.

Comets

You may have heard about a newly discovered comet, C/2021 A1 (Leonard) which is predicted to reach naked eye visibilty, maybe even become quite bright, at its closest to Earth in mid December.  It was found on Jan 3rd by Greg Leonard at the Mount Lemmon observatory in Arizona. It is thought to have a hyperbolic (open ended) orbit, ejected from the Oort Cloud about 3,500 years ago and travelling towards the Sun since then. After perihelion it will begin the long journey back, never to return - unless it's disturbed again. 
At the moment it is circumpolar, in Bootes and highest in the sky just before dawn, but very faint - around mag 18.7.

The other comets around at the moment are also faint.
C/2020 M3 (ATLAS) is in Auriga, circumpolar and high for most of the night, but only at mag 13, fading to 14.7 by the end of Feb.

141P/Machholz is also quite high.  Starts the month in Cetus at mag 11.8, passes through Eridanus and Taurus and ends the month in Orion, down to mag 14.7

C/2020 S3 (Erasmus) and 88P/Howell are not only faint but also too low in our sky for observation or imaging.

Most of the information here comes from the website https://in-the-sky.org
It has coordinates for all solar system objects on any day, finder charts and lots of other information.
Also useful is https://theskylive.com   though I don't find that one quite so user friendly.
www.cometwatch.co.uk again hasn't been updated this month.

Meteor Showers

February is a very poor month for meteors. The only active shower has a radiant so far south that it's very unlikely that anything will be seen from our northern latitude.

Alpha Centaurids:  active Jan 21st to Feb 20th, peak FEb 8th, ZHR 6 but occasionally as many as 25.

The radiant of the Antihelion Source passes through southern Leo during February, but has a ZHR of only 2 or 3.































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