Mercury passes through superior conjunction on March 7th, but it's not long before the fast moving planet moves out from the Sun and into the early evening sky. During the second half of the month, it re-appears low down towards the western horizon after sunset from northern locations. For example, on March 31st from London (51.5N) England, Mercury will be positioned 7.5 degrees above the horizon, one hour after sunset.
Between March 15th and 31st, observers should note that although the planets altitude improves slightly each subsequent evening, it brightness dims from mag. -1.5 to -0.4.
From southern temperate latitudes, Mercury is unsuitably placed for observation.
The current long evening apparition of Venus comes to an end this month. The brightest planet starts March as a dazzling beacon of light, visible after sunset above the western horizon. It shines at mag. -4.8, with an illuminated phase of 16 degrees and an apparent diameter of 47 arc seconds. As the month progresses, Venus falls back towards the Sun, fades in brightness and decreases in phase, but its apparent diameter improves to a maximum of 60 arc seconds. The apparition finally ends on March 25th, when inferior conjunction is reached. However, it's only about a week or so before Venus can be seen again, this time in the early morning sky.
Mars continues to move eastwards and northwards with respect to the "fixed" stars. The "Red planet" starts the month in Pisces before crossing into Aries on March 8th, where it stays for the rest of the month. Throughout March, Mars is visible as an early evening object towards the west, although its brightness decreases from mag. +1.3 to +1.5 and its apparent diameter shrinks from 4.6 to 4.2 arc seconds. Telescopically, the Martian disk is now too small to spot details.
On March 1st, Mars is located 12 degrees east of much brighter Venus (mag. -4.8). Also visible in the same binocular field of view as Mars is Uranus (mag +5.9), with Mars acting as a useful aid in locating the much fainter outer planet. This month, Mars manages to keep ahead of the Sun while Venus falls back towards the western horizon. From northern temperature locations, Mars sets 4 hours after the Sun on March 1st, reducing to 3 hours by month's end. However, the visibility period is up to 2 hours shorter for those located further south.
On March 1st and 30th, the waxing crescent Moon passes a few degrees south of Mars.
Jupiter is now a brilliant object as it heads towards opposition in April. The giant planet is moving retrograde in Virgo. It rises mid-evening at the start of the month and by month's end is practically visible all night. The planet's current declination of a few degrees south of the celestial equator means it's at least reasonably well placed for observation from most locations Worldwide.
This month, Jupiter brightens from mag. -2.3 to -2.5 with its apparent diameter increasing from 42.1 to 44.1 arc seconds. It easily outshines all night-time stars. A pair of binoculars is all that's required to reveal the four largest moons of Jupiter. They are Io, Europa, Ganymede and Callisto. Occasionally all of them are visible at the same time, but some can be hidden from view as they pass in front of or behind the Jovian disk. Telescopically, the planet is a gem. Even small refractors will show the main cloud belts. Medium and large scopes reveal much detail, including smaller belts, ovals, festoons and the famous "Red Spot".
On March 14th, the waning gibbous Moon passes 3 degrees north of Jupiter.
Saturn, mag. +0.5, continues to move direct in western Sagittarius, close to the Ophiuchus border. The beautiful "Ringed planet" remains a morning object, although by month's end it's visible from around midnight from southern temperate locations. However, those located further north will have to wait up to 3 hours longer to spot the planet. To the naked eye, Saturn appears creamy or off-white in colour.
When seen through a telescope, Saturn is a wonderful sight. A small 80mm (3.1-inch) scope easily reveals the ring system, which is currently wide open at a tilt of 26-degrees. A 150mm (6-inch) or 200mm (8-inch) instrument shows a wealth of details such as planetary cloud formations, ring divisions and up to half a dozen satellites. During the month, the apparent diameter of the Saturnian disk increases slightly from 16 to 17 arc seconds.
On March 20th, the last quarter Moon passes 3 degrees north of Saturn.
Uranus, mag. +5.9, remains an early evening binocular object during March. The seventh planet from the Sun is located in Pisces and visible towards the west as soon as it's dark enough. On March 1st, Mars is positioned just 1.5 degrees northeast of Uranus, but it's not long before the much nearer and faster moving Mars moves away.
For those located at temperate northern latitudes, Uranus can be seen for about 4 hours on March 1st, reducing to around 3 hours by months end. From southern locations, its visibility period is only about half as long.
On March 1st, the thin waxing crescent Moon passes 4 degrees south of Uranus.
Neptune continues to move slowly direct in Aquarius as it heads towards solar conjunction on March 2nd.
For observers at tropical and southern locations, the distant planet reappears during the second half of the month, low down above the eastern horizon just before sunrise. At mag. +8.0, it's beyond naked eye visibility, but can be glimpsed with binoculars and small scopes.
From northern temperate latitudes, Neptune remains inconveniently placed throughout March and not observable.
Solar System Data Table March 2017
|Date||Right Ascension||Declination||Apparent Magnitude||Apparent Size||Illum. (%)||Distance from Earth (AU)||Constellation|
|Sun||5th Mar 2017||23h 02m 24.8s||-06d 09m 08.4s||-26.8||32.3'||100||0.992||Aquarius|
|Sun||15th Mar 2017||23h 39m 17.2s||-02d 14m 26.8s||-26.8||32.2'||100||0.994||Pisces|
|Sun||25th Mar 2017||00h 15m 46.4s||01d 42m 26.0s||-26.8||32.1'||100||0.997||Pisces|
|Mercury||5th Mar 2017||22h 58m 33.7s||-08d 32m 53.3s||-1.7||04.9"||100||1.372||Aquarius|
|Mercury||15th Mar 2017||00h 08m 21.8s||00d 09m 02.4s||-1.5||05.2"||96||1.287||Pisces|
|Mercury||25th Mar 2017||01h 14m 13.9s||09d 10m 48.5s||-1.0||06.2"||71||1.084||Pisces|
|Venus||5th Mar 2017||00h 36m 18.8s||11d 34m 53.7s||-4.7||49.8"||13||0.335||Pisces|
|Venus||15th Mar 2017||00h 25m 40.0s||11d 47m 40.8s||-4.4||56.4"||05||0.296||Pisces|
|Venus||25th Mar 2017||00h 04m 58.2s||09d 37m 08.3s||-4.2||59.4"||01||0.281||Pisces|
|Mars||5th Mar 2017||01h 36m 48.6s||10d 09m 25.6s||+1.3||04.5"||95||2.062||Pisces|
|Mars||15th Mar 2017||02h 04m 14.0s||12d 48m 56.4s||+1.4||04.4"||95||2.126||Aries|
|Mars||25th Mar 2017||02h 31m 56.8s||15d 15m 56.2s||+1.4||04.3"||96||2.188||Aries|
|Jupiter||5th Mar 2017||13h 22m 53.5s||-07d 04m 29.0s||-2.4||42.5"||100||4.636||Virgo|
|Jupiter||15th Mar 2017||13h 19m 29.5s||-06d 42m 20.9s||-2.4||43.3"||100||4.549||Virgo|
|Jupiter||25th Mar 2017||13h 15m 20.5s||-06d 16m 05.8s||-2.4||43.9"||100||4.489||Virgo|
|Saturn||5th Mar 2017||17h 45m 47.8s||-22d 05m 11.8s||+0.5||16.3"||100||10.217||Sagittarius|
|Saturn||15th Mar 2017||17h 47m 41.8s||-22d 05m 10.1s||+0.5||16.5"||100||10.052||Sagittarius|
|Saturn||25th Mar 2017||17h 48m 55.1s||-22d 04m 51.0s||+0.5||16.8"||100||9.886||Sagittarius|
|Uranus||5th Mar 2017||01h 22m 23.9s||08d 03m 28.8s||+5.9||03.4"||100||20.710||Pisces|
|Uranus||15th Mar 2017||01h 24m 16.3s||08d 14m 50.6s||+5.9||03.4"||100||20.804||Pisces|
|Uranus||25th Mar 2017||01h 26m 16.7s||08d 26m 54.3s||+5.9||03.4"||100||20.874||Pisces|
|Neptune||5th Mar 2017||22h 53m 21.6s||-08d 00m 15.1s||+8.0||02.2"||100||30.941||Aquarius|
|Neptune||15th Mar 2017||22h 54m 46.1s||-07d 51m 45.2s||+8.0||02.2"||100||30.921||Aquarius|
|Neptune||25th Mar 2017||22h 56m 08.2s||-07d 43m 32.0s||+8.0||02.2"||100||30.872||Aquarius|