The night sky in April 2017

posted 1 Apr 2017, 08:30 by Pete Collins   [ updated 3 Apr 2017, 12:37 ]
by Anne Holt

Sunrise:  1st    06.42         30th    05.36
Sunset    1st    19.44         31st    20.37

Astronomical darkness 
1st:     21.50  to  04.33        30th:   23.33  to  02.50

Full Moon   11th       New Moon   26th

Highlights

'Light' is the key word here - we're approaching the time of year when there's far too much of it for astronomers' liking.

We have one bright planet, a couple of binocular comets, an ancient meteor shower, and a chance of some fireballs.

On 28th the 8% lit moon occults Aldeberan - the eye of the bull - in Taurus, between 19.08 and 20.00.   This is, as you have probably realised, is in daylight but should be visible in scopes.

There are some bright early evening passes of the International Space Station from 1 - 9 April.
 

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 beautiful area round the Winter Hexagon, so rich in bright stars, is sinking slowly in the West.

Winter Hexagon

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

One planet puts on a really good show this month - and this time it isn't Venus!

Mercury:  in Aries, mag -0.1. Best seen in the first week of April.  At greatest Eastern elongation on 1st,  when it sets at 21.35.  It is still very low in the Western sky and should be visible between 20.00 and 20.30.  During the rest of the month it won't be easy to see - it fades rapidly as it approaches inferior conjunction on 20th.   It then becomes a morning object, moving into Pisces on 22nd and rising only 20 minutes before the sun at month end.

Venus:  in Pisces, mag -4.0. Another one which isn't easily seen during April.  It rises about an hour before the sun throughout the month but is very low in the dawn sky, so, despite its brilliance, it is nowhere near as prominent as it has been in the evening sky during the last few months.

Mars:  in Aries,  mag 1.5. Best seen in the early part of the month.  It sets at around 23.00 throughout April but by the end of the month, when the sun isn't setting until after 20.00, is quite low in the West as the sky darkens.   Moves into Taurus on 13th, and on 20th is slightly less than 4 degrees South of the Pleiades

Jupiter:  in Virgo, mag -2.4. The star of the April sky, shining brightly for most of the night throughout the month,  rising soon after sunset at the start of April.  It is at opposition on 7th and by month end is quite high in the sky as it gets dark, culminating half an hour before midnight.    In the early hours of 11th the full Moon passes just 1.5 degrees north of the planet. On the morning of 4th both Io and Ganymede pass into Jupiter's shadow,  Io at 01.40 and Ganymede at 05.38.  Io reappears from behind the planet's disc at 03.57.  On the night of 14th/15th Ganymede and its shadow cross the face of Jupiter,  Ganymede from to 22.57  to  01.01, the shadow following about an hour later.  Ganymede also transits on 22nd between 02.12 and 05.49.

Saturn:  in Sagittarius,  mag 0.4. Rises around 02.30 in early April and a couple of hours earlier at the end of the month.  Still very low in the sky - only 15 degrees above the horizon at its highest point.   However the rings are still wide open so it is well worth viewing through a telescope if you have a clear southern horizon.

Uranus:  in Pisces,  mag 5.9. Sets about an hour after the Sun so is barely visible this month.

Neptune:  not visible.

Meteor Showers

One fairly strong shower this month.

The Lyrids, active 16th to 25th, peak on the night of 22nd/23rd but should also be quite good on the nights before and after.   ZHR 20,  occasionally much higher but the enhanced rates are not predicted for this year.   As with most showers, the best time to observe is between midnight and dawn.  The Moon will not interfere.
These meteors originate from Comet C/1801G1 Thatcher,  it is the oldest known shower, recorded by Chinese astronomers in 687BC.  It is also the strongest shower from a long period comet.

Minor Showers

Librids:  active 15th to 30th with several short peaks.

Delta Draconids:  active March 28th to April 17th with no definite peak.  These are very slow meteors which leave conspicuous trails.  they were first recorded in 1971.

Spring antihelion source, meteors appearing to come from the area of the ecliptic directly opposite the position of the sun, are active early to mid April and again near the end of the month.  ZHR 3 - 4.

And finally, we may have some fireballs - meteors of magnitude minus 3 or brighter. 

The April fireballs are active 14th to 20th.  These have no specific radiant, but appear to emanate from the South Eastern part of the sky.  They sometimes reach the ground as meteorites.

Alpha Bootids, peak on 28th.   This shower could also include fireballs - slow moving and leaving smoky trails.

Comets

41P / Tuttle-Giacobini-Knesal starts April in Draco, just above the bowl of the Plough - close to the location of the Hubble Deep Field.  During the month it moves eastwards and is SW of Vega on 30th.  Its magnitude is expected to reach a peak of 6.6 between 5th and 11th,  then fade to 7.6 by month end.

C/2015 V2 Johnson moves much more slowly through Hercules during April.  It should brighten slowly from 8.3 to 7.4

Both should be visible in binoculars.

For more detailed info on planet and comet positions see

International Space Station passes


Times are correct for North Manchester. See www.heavens-above.com for more information and to set your observing location.

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