The night sky in April 2020

posted 30 Mar 2020, 06:03 by Pete Collins
by Anne Holt

Sunrise      1st:    06.41          30th:     05.35
Sunset       1st:    19.45          30th:     20.37

Astronomical darkness    1st:  21.51  to  04.33        30th:  23.24  to  02.47

Day length   1st:  13.03.35       30th:  15.02.04

Full Moon:       8th at 03.35  (363511 km).    
New Moon:    23rd at 03.27  (403817 km)

Lunar perigee:    7th at 19.10    (356908 km)
Lunar apogee:  20th at 20 02    (406461 km)
 
April's full Moon is known as the Pink Moon because of the pink flowers which bloom at this time.  Other names are the Sprouting Grass Moon, the Fish Moon, the Hare Moon, and the Old English/Anglo Saxon Egg Moon or Paschal Moon.  This is the full Moon which is used to calculate the date of Easter.

Highlights

We actually have some highlights this month - for those who have a dark garden to observe from.  Having to stay at home is not so good for those of us who have a street light outside the front garden and neighbours at the back who seem to leave their lights on all night.
Venus is still dominating the evening sky, reaching its brightest on 28th.  Jupiter, Mars and Saturn are all low in the SE in the morning, though only Jupiter is bright enough to really stand out.
This month's full Moon is is the biggest Supermoon of the year, occurring just under eight and a half hours after the year's closest perigee, and at last we have a promising meteor shower.  A newly discovered comet is brightening nicely and may become a naked eye object by month end.
We have Easter Sunday on 12th.  The astronomical connection is that it is the Sunday after the first full Moon on or after the Vernal Equinox, which is taken as 21st March even when, as this year, it actually falls on 20th. 
In case anyone is interested, the earliest date for Easter Sunday is March 22nd.  This is very rare - the last time was in 1818, the next won't be until 2285. The latest date, April 23rd, is more common, some people alive now might just manage to see one or 2 of these - last was in 1943, next in 2038.
And the sequence is not totally random:  it begins to repeat itself after 5,700,000 years.  If we still used the Julian calendar it would repeat after only 532 years!
Finally, April sees the 50th anniversary of the Apollo 13 mission, when a near tragedy became what many people consider to be NASA's greatest triumph.  It lifted off on 11th, at 13.13 local time - and we all know what happened 2 days later. 

Constellations

Now that BST has been forced upon us, we have to wait even longer for the skies to darken each evening. By the time it gets really dark the winter constellations, including the beautiful area around the Winter Hexagon, so rich in bright stars, is sinking slowly in the West.

Ursa Major is now high in the sky with the Plough overhead around midnight in the second half of the month. Follow the curve of the handle down to the orange coloured Arcturus, brightest star in the constellation Bootes the herdsman, and the 4th brightest in the night sky.
The signature constellation of spring, Leo, is still riding high in the south and the Summer Triangle of Vega (in Lyra), Deneb (Cygnus) and Altair (Aquila) is now rising in the east and visible in the early hours.

Planets

Mercury:  in Aquarius, mag 0.00
A morning object but too low for observation.  On 1st it rises at 06.16 but is still below the horizon when the sky begins to brighten. Its position gets even worse during the month, it moves into Pisces on 10th, when it is at mag -0.2, and Aries on 29th, at mag -1.5. On 30th it rises at 05.32 but appears only 5 degrees from the Sun.

Venus:  in Taurus, mag -4.4
So bright that it can easily be seen through the window of a lighted room - assuming that it faces west. On 1st it is at 36 degrees soon after 20.00 and during the first few days of the month it passes south of the Pleiades.  It continues to brighten, reaching mag -4.5 by 10th, when it is slightly lower, 28 degrees at around 21.00.  On 26th the 3 day Moon passes south of the planet, closest, 6 degrees, at 16.23.  It reaches maximum brightness on 28th, when it is at mag -4.52, a little short of the maximum possible of -4.7.  On 30th, only marginally fainter, it sets at 00.52.

Mars:  in Capricorn, mag 0.8
Very low in the morning sky, rises about 2 hours before the Sun throughout April and doesn't get higher than 7 degrees above the horizon as the sky brightens.  On 1st it rises at 04.41.  On 16th the Moon passes south of the planet, separated by 3 degrees at 5am.   On 30th it rises at 03.37 and has brightened to mag 0.4.

Jupiter:  in Sagittarius, mag -2.2
Another morning object, much easier to see as it is slightly higher and much brighter than Mars. On 1st it rises at 04.16 and should reach 11 degrees in the SE before the sky begins to brighten a couple of hours later.  On 15th the 21 day Moon passes south of Jupiter, closest at 00.05 when they are below the horizon.   At 5am the Moon is between Jupiter and Saturn, with Jupiter 4 degrees NW of the Moon, Saturn 4 degrees NE.  On 30th Jupiter rises at 02.30 and should be easily visiible from around 03.50,slightly brighter at mag -2.4.

Saturn:  in Capricorn, mag 0.7
The third major planet currently low in the morning sky. On 1st it rises at 04.34 and only reaches 8 degrees in the SE by dawn. It improves slightly during April, on 15th when the Moon passes south of the planet, it will be at about 11 degrees as the sky brightens. The pair are closest, 2 degrees 27', in daylight at 10.18. On 30th it rises at 02.43, slightly brighter at mag 0.6, but still only gets to 11 degrees while the sky is reasonably dark.

Uranus:  in Aries, mag 5.9
Not visible this month.  On 1st it is only 6 degrees above the horizon at dusk.  Its apparent separation from the Sun decreases still further during the month as it approaches solar conjunction on 26th, only 26' at its closest.  On 30th it rises at 05.35,  just a couple of minutes before the Sun, and is separated from it by just 2 degrees.

Neptune: in Aquarius, mag 8.0
Still too close to the Sun to be visible.  On 1st it rises at 06.15 but is still 9 degrees below the horizon at dawn. On 30th it rises at 04.23, more than an hour before sunrise, but still fails to get above the horizon before the sky begins to brighten.

Dwarf Planets

Ceres: in Capricorn, mag 9.3
The closest of the 5 dwarf planets, the only one which orbits in the Asteroid Belt, is still too low for telescopic viewing or imaging.  It moves into Aquarius on 9th and by month end rises a couple of hours before the Sun but is still very low in the brightening sky.

Pluto: in Sagittarius, mag 15.1
Still too low to be succesfully imaged which, because it moves so slowly round the sky, it will be for many years yet.

Haumea, in Bootes at mag 17.3, and Makemeke, in Coma Berenices at mag 17.2 are much higher, therefore better targets for the most experienced astrophotographers. Because their orbits are very inclined to the ecliptic (28 degrees and 29 degrees respectively) these can be found quite far from the ecliptic. Haumea reaches opposition on 16th, when it will be 52 degrees above the southern horizon at 01.52.  Makemake culminates slightly higher, 60 degrees, throughout the month.  Both will be high in the sky for much of the night.

Eris:  in Cetus, mag 18.8
The most distant of the 5 officially recognised dwarf planets, the largest known solar system object which has never been visited by a spacecraft, appears too close to the Sun this month.

Asteroid 3 Juno, the third to be discovered but only the 13th in order of size, reaches opposition on 3rd.  It's in Virgo, mag 9.7.  On this night it culminates at 01.26, at 38 degrees in the South.

Comets

C/2019 Y4 (ATLAS) in Camelopardalis, mag 8.7.
Discovered in December 2019, this one is looking very promising.  It has been brightening rapidly recently and is predicted to reach naked eye brightness by late April.  It is a long period comet with a similar orbit to the Great Comet of 1844 so it is thought that it could be another fragment of the same parent body.
Will it live up to its promise?
Will it become another Great Comet?
We can but hope.
At the moment it is circumpolar, close to the north celestial pole so reasonably high in the sky throughout the night. If it continues to brighten at the current rate it could end the month at mag 4.4.  It should be visible until late May when, if it behaves as predicted, could have reached mag -3.7.  Current estimates give the peak brightness as -5.5.  The bad news is that this is in early June, when it will be below the horizon in darkness from our latitude.
For anyone who wants to try their luck at imaging it while it's still quite faint, exact co-ordinates for each night are given in https://in-the-sky.org/ephemeris.

C/2017 T2 (PANSTARRS) in Cassiopeia, mag 9.1
Again circumpolar, so above the horizon all night.  Moves into Camelopardalis on 11th. This one is also predicted to brighten during April but nowhere near as much - estimated mag for 30th is 8.9

C/2019 Y1 (ATLAS)
Another circumpolar one, but this is fading not brightening. It starts the month in Andromeda at mag 9.0, then moves into Cassiopeia on 2nd.  Not as high in the sky as the others but still reasonably so for much of the night.  In Cepheus from 26th, when it will have faded, probably to around mag 10.9.  Finishes the month at mag 11.3.

Recommended sites for exact positions, finder charts, and more information on all Solar System objects


And for comet news


Meteor Showers

One reasonable shower this month.
Lyrids, active 14th to 30th (or maybe only till 25th - even the IMO doesn't always agree with itself)  ZHR 18, but usually also quite good on the nights before and after the peak. The shower occasionally shows much higher rates - in 1982 a ZHR of 90 was recorded, but nothing like that is predicted for this year.
It's likely that this shower was very much stronger in the past, in 687AD Chinese astronomers reported that meteors fell like rain.  These are medium speed meteors, usually without trails, but the shower could include some fireballs. They are best seen in the early hours.
The parent comet is C/1810 Thatcher, last seen in 1861, next return 2276.
The good news is that the peak is just before New Moon, so no interference.

Not much in the way of minor showers, at least not for those of us living in the northern hemisphere.
The southern hemisphere has the pi Puppids, active 15th to 28th, peak 23rd, ZHR variable.

Here, we may see a few meteors from the antehelion source, the radiant of which moves from SE Virgo into Libra during April.

It is also thought that there could be some activity in the early hours of 24th from the alpha Virginids. The radiant of these is far enough from that of the ANT for it to be considered a separate shower.  Parent body is minor planet 2010 GE35.



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