|March 2017 Sky Guide|
(Please note all times are UT unless otherwise stated and are based on an observing location of Belfast and covers the month of March)
Mercury is at superior conjunction on the 7th and is visible in the evening sky in the 2nd half of the month. This will be its best PM appearance of 2017. At month's end, it sets at 21:50 ST and is mag +0.0.
Venus is at inferior conjunction on the 25th. It is visible in the evening sky at the start of the month and becomes a morning object by month's end. It sets at around 21:25 at the start of the month, by month's end it rises at 06:00 ST. It fades from mag -4.4 to mag -4.1 during the month.
Mars is visible in the evening sky this month, moving from Pisces to Aries. It is visible as soon as darkness falls during the month and sets at 23:15 ST by month's end. It fades from mag +1.4 to mag +1.6 during the month.
Jupiter is visible in the evening sky this month in Virgo. At the start of the month, it rises at 21:50, by month's end; it rises at 20:35 ST. It brightens from mag -2.2 to mag -2.3 during the month.
Saturn is at western quadrature on the 17th and is visible in the morning sky this month in Sagittarius. At the start of the month, it rises at 03:50, by month's end it rises at 03:00 ST. It brightens from mag +1.3 to mag +1.2 during the month.
Uranus is visible in the evening sky at the start of the month in Pisces, but is not safely observable by month's end. At the start of the month, it is mag +5.9 and sets at 21:50. A finder chart for Uranus is available from the below Information Sources and Links Section.
Neptune is at conjunction on the 2nd and is not visible this month.
The first quarter moon is on the 5th with the full moon on the 12th. The last quarter moon is on the 20th with the new moon on the 28th.
1st pm the waxing crescent lies SE of Uranus and Mars at 19:00.
4th pm the waxing crescent lies SW of Aldebaran (Alpha (α) Tauri, mag +0.9) at 19:00.
10th pm the waxing gibbous lies W of Regulus (Alpha (α) Leonis, mag +1.4) at 19:00.
14th pm the waning gibbous lies NE of Jupiter and Spica (Alpha (α) Virginis, mag +1.0) at 22:00.
19th am the waning gibbous lies NE of Antares (Alpha (α) Scorpii, mag +1.0) at 03:00.
20th am the waning gibbous lies NW of Saturn at 04:00.
29th pm the waxing crescent lies E of Mercury at 20:00.
30th pm the waxing crescent lies SE of Mars at 21:00.
The best time to observe meteor showers is when the moon is below the horizon; otherwise its bright glare limits the number you will see especially the fainter ones. Below is a guide to this month's showers.
There are no bright meteor showers this month.
There may be additional minor showers this month, details of which can be found in the below Information Sources and Links Section.
Asteroid (41) Daphne is at opposition on the morning of the 8th at 06:00. It will be mag +9.6 in Leo and will be visible as soon as darkness falls on the evening of the 7th.
Finder charts and further information about other fainter asteroids can be found in the below Information Sources and Links Section.
Comet C/2015 V2 (Johnson) is currently mag +10 and brightening slowly. In March, it will be in Hercules and will be circumpolar. It will be low in the sky in the early evening, but gains altitude as the night goes on. On the evening of the 3rd, it will be close to Tau (τ) Herculis, mag +3.9. It is predicted to peak at mag +7 during the summer.
Comet C/2015 ER61 (PanSTARRS) is currently mag +10 and brightening. In March, it will be a morning object moving from Sagittarius to Capricornus. It will be visible around 06:00 during the month. It is predicted to peak at between mag +5 and +7 in May.
Comet 41P/Tuttle-Giacobini-Kresak is currently mag +12 and brightening. It is expected to reach mag +6 in April. In March, it is circumpolar and moves from Leo to Leo Minor and into Ursa Major by month's end. On the evenings of the 12th and 13th, it lies near to Lambda (λ) Ursae Majoris, mag +3.5. On the evening of the 21st, it passes near to M108 and on the following evening, near to M97 and Merak (Beta (β) Ursae Majoris, mag +2.3). It passes through the main "body" of the plough between the nights of 22nd – 26th.
Finder charts and further information about the above and other fainter comets can be found in the below Information Sources and Links Section. Any of the above estimates are based on current information at the time of writing the guide and can be wrong - "Comets are like cats; they have tails, and they do precisely what they want", David H Levy.
On the deep sky front this month, galaxies M81 and M82 can be observed in Ursa Major. In Andromeda, M31 - The Andromeda galaxy can be observed along with its satellite galaxies M32 and M110. In Perseus, there is the open cluster M34 and the excellent Double Cluster - NGC 869 and 884. In Auriga there are three open clusters M36, M37 and M38 and also M35 in Gemini. Taurus has the excellent Pleiades - M45, the Hyades and also M1 - The Crab Nebula. In Orion we have M42 - The Great Orion Nebula and also Cancer with M44 - The Beehive Cluster and M67. Check out the constellation Canes Venatici with the globular cluster - M3 and several galaxies including M51 - the Whirlpool Galaxy and M63 - the Sunflower Galaxy. In Leo, we have several galaxies on view including The Leo Triplet - M65, M66 and NGC 3628. M95, M96 and M105 can also be observed in Leo. The place to really find galaxies is in Virgo. The Virgo Super Cluster can be found here with numerous galaxies on view. Also in Virgo, M104 - the Sombrero Galaxy can be found. In Coma Berenices, there is M64 - the Black-Eye Galaxy.
Both are caused by sunlight reflecting off dust particles which are present in the solar system. The Zodiacal Light can be seen in the West after evening twilight has disappeared or in the East before the morning twilight. The best time of year to see the phenomenon is late-Feb to early-April in the evening sky and September/October in the morning sky - it's then that the ecliptic, along which the cone of the zodiacal light lies, is steepest in our skies. The Gegenschein can be seen in the area of the sky opposite the sun. To view either, you must get yourself to a very dark site to cut out the light pollution. When trying to observe either of these phenomena, it is best to do so when the moon is below the horizon. A new appendix has been added explaining some of the more technical terms used in the guide.
Information Sources Used
www.skyviewcafe.com ; Sky at Night Magazine Observing Guide and CD;
Philip's Stargazing 2014;
The ZHR or Zenithal Hourly Rate is the number of meteors an observer would see in one hour under a clear, dark sky with a limiting apparent magnitude of 6.5 and if the radiant of the shower were in the zenith. The rate that can effectively be seen is nearly always lower and decreases as the radiant is closer to the horizon. The Zenith is the overhead point in the sky.
The radiant is the point in the sky, from which (to a planetary observer) meteors appear to originate, i.e. the Perseids, for example, are meteors which appear to come from a point within the constellation of Perseus. When the radiant is quoted as "circumpolar", it is never below the horizon and visible all night, otherwise the times quoted are when the constellation in which the radiant lies rises above the horizon in the East.
A fireball is defined by the International Astronomical Union as a meteor brighter than any of the planets, i.e. magnitude -4 or brighter. The International Meteor Organisation alternatively defines it as a meteor which would have a magnitude of -3 or brighter at the zenith.
The ° symbol in the guide is that for degrees. A degree is two full moon widths to give an idea for judging any distances quoted in the guide. There are 60 arcminutes in a degree.
An asterism is a collection of stars seen in Earth's sky which form simple patterns which are easy to identify, i.e. the Big Dipper. They can be formed from stars within the same constellation or by stars from more than one constellation. Like the constellations, they are a line of sight phenomenon and the stars whilst visible in the same general direction, are not physically related and are often at significantly different distances from Earth.
Mag is short for magnitude which is the measure of an object's brightness. The smaller the number, the brighter the object. The brightest object in the sky is the Sun at mag -26, the full moon is mag -12 and Venus the brightest planet is mag -4. The brightest stars are mag -1. If there is a 1 mag difference between two objects - there is a difference in brightness of a factor of 2.5 between the two objects. For example the full moon is eight magnitudes brighter than Venus on average which means it is 1,526 times brighter than Venus. Objects down to mag +6 can be seen with the naked eye under very dark skies.
Local time is always quoted in the guide and this means for November - February - universal time (UT)/GMT is used and for April to September - daylight savings time (DST, = GMT+1). For the months of March and October when the clocks go forward/back respectively, both times will be used and attention should be paid to any times at the end of these months for that change.
Deep Sky Objects such as galaxies, nebulae and star clusters are classified in catalogues such as the Messier catalogue for objects like M44 - M for Messier. Another example of a catalogue would the New General catalogue whose objects have the prefix NGC. There are links for websites to both catalogues in the section above.