The night sky in March 2017

posted 28 Feb 2017, 07:24 by Pete Collins   [ updated 28 Feb 2017, 07:30 ]
by Anne Holt

Sunrise:   1st    06.56      31st    06.44
Sunset     1st    17.47      31st    19.42

Astronomical darkness:  
                 1st:  19.43   to   04.58
               31st   21.48   to   04.36

Full Moon  12th      New Moon  28th

Highlights

As in previous years, it's a struggle to find any real highlights in March.  Venus is losing its place as the bright evening 'star' but Jupiter is rising earlier and is beginning to dominate the late evening sky. We also have two binocular comets. There are plenty of visible ISS passes this month, but they are in the hours before dawn.

However at this time of year the skies tend to be cloudy rather than bright and starry and darkness falls later and later throughout the month.  By month end the Sun sets before 20.00 - though that is partly because of the compulsory 'do everything an hour earlier'  aka British Summer Time which is imposed on us from Sunday 26th. 
The Vernal (Spring) Equinox, defined as the moment when the plane of the Earth's equator passes through the centre of the Sun's disc, is at 10.29 on March 20th.  Despitre the name day and night are not quite equal then - the day is actually 12 hr: 11 min : 20 secs long.  The closest to 12 hours is March 17th, which is just 88 seconds short.

Constellations

We are now losing the winter highlights of Orion, Sirius and Taurus soon after midnight, though they are still promiinent in the south in the early part of the night.
Auriga, with the bright yellowish-white star Capella, is now overhead soon after sunset, with Gemini and Leo also prominent. The not very obvious zodiac constellation, Cancer, is now well placed. The Plough is overhead by midnight, the handle pointing to the orange hued Arcturus, the brightest star north of the celestial equator, in the constellation of Bootes. By the end of March the Summer Triangle will be above the horizon soon after 2am - or by 1am if you've forgotten to put the clock forward.

Planets

Mercury:  in Aquarius  mag -1.4. Not visible early in the month as it approaches inferior conjunction on 7th,   on 1st it rises only 5 minutes after the Sun.  By mid March it may be seen in the evening setting 40 minutes after the Sun on 14th and at 21.35, almost 2 hours after Sunset, on 31st.  By this time it will be around mag -0.4 and best seen around 20.00. Around these dates is probably the best time this year to track down this elusive planet - it's bright, but not easy to see so close to the horizon.

Venus:  in Pisces  mag -4.4. Still very bright in the evening sky at the start of March but rapidly losing height above the western horizon as the month progresses.  Reaches inferior conjunction (the closest point in its orbit to the Earth) on 23rd, when, because of the inclination of its orbit, it will appear to be directly above the sun and may be seen in both the morning and evening twilight for a couple of days.   By month end it is a morning object, rising about an hour before the sun and showing a 2% lit crescent.

Mars  in Pisces, moving into Aries on 9th, mag 1.3. On 1st it sets at 21.50, 4 hours after the sun, and will be only 2 degrees above Uranus - a good binocular target, weather permitting.  By month end it will be setting at 23.00 (now BST, so actually around the same time throughout the month)  but slightly dimmer, at mag 1.5.

Jupiter:  in Virgo  mag -2.3. Now becoming prominent in the late evening sky. At the start of March it rises at 21.27 and by month end will be above the horizon soon after 20.00, culminating (reaching its highest point in the sky) at 10.42.  There are several transits this month, as the Galilean moons and their shadows pass between us and the planet.
These include:
2nd/3rd   Ganymede's shadow  22.30  to  01.10
               Ganymede                02.06  to  04.02

10th        Ganymede's shadow  02.37  to  05.06
               Ganymede                05.30  to  07.26

19th/20th  Io's shadow             23.44  to  01.55 
                 Io                           00.11  to  02.21

So, between 00.11 and 01.56, both Io and its shadow will be seen against the face of the planet - a good photo opportunity, perhaps.

Saturn:  in Sagittarius  mag 0.5. Not particularly prominent this month.  It's a morning object throughout, rising just before 03.30 on 1st.  By month end, when it rises at 02.30, it culminates at 06.19 just under half an hour before Sunrise.  It will still be very low in the sky, reaching an altitude of only 22 and a half degrees but worth seeing as the rings are still favourably positioned, angled at around 26 degrees.

Uranus:  in Pisces  mag 5.9. Appears close to Mars in early March but is only 17 degrees above the horizon as the sky darkens, setting at 21.39.  By month end it sets just over an hour after the sun and won't be visible in the twilit sky.

Neptune: Not visible this month.

Comets

C/2015V2 Johnson is still around, spending March moving through Hercules. It is expected to brighten during the month, from mag 9.1 to mag 8.1. It isexpected to reach mag 6 by May (but comets are notoriously unpredictable!)

41PTuttle-Giacobini-Knesak starts the month at mag 10, positioned to the north of Leo's Sickle asterism, then moves towards Ursa Major ending the month just above the bowl of the Plough.   It will be much brighter at mag 6.9,  unfortunately still below the limit of naked eye visibility - even for those lucky enough to live in an area where the skies are really dark.

For more details of positions of planets, comets etc see:

Meteors

No major showers this month, and not much in the way of minor ones either.

The Gamma Normids, which peak on March 16th, are only visible from the Southern Hemisphere, and the Camelopardids, peaking on 22nd, have a ZHR of only 1. Their main (only!) claim to fame is that they are the slowest known meteors, moving at only 7km/sec. 

The best chance of seeing a few meteors is probably the Spring Antihelion Source, radiant on the ecliptic directly opposite the position of the sun,  ZHR 3 to 4.
Comments