The Night Sky This Month: February 2016

Hyginus Rille
Hyginus Crater by NASA/GSFC/Arizona State University

February’s low temperature are a reminder to stargazers that winter has fully arrived. Nonetheless, those brave souls who have no problem with the cold will always find something interesting to see, including a rare planetary array involving  five planets.

The Moon

Phases

New Moon: February 8th
First Quarter: February 15th
Full Moon: February 22nd
Last Quarter: February 1st

The Hyginus Rille

This month offers an excellent opportunity to view a crater on the moon that is suspected to be of volcanic origin, as opposed to being the result of an impact. While it is accepted by the majority that the vast majority of moon craters were formed by impacts, there are some exceptions to the rule. In the case of the Hyginus crater, it is thought that a violent sub-surface release of explosive gas had excavated a cavity into which the overlying surface had collapsed. The absence of a rim, and the fact that the pit is bisected by a rille suggests internal geologic activity as the creation mechanism of the crater.

Planets

Observing the planets may be its own reward, but up until February 20th a rare planetary array involving Jupiter, Mars, Saturn, Venus and Mercury can also be seen pre-dawn stretching all the way from the Moon along to the southern horizon. So check out the information below to see what is visible when, and where.

The Night Sky This Month: February 2016

Mercury

At magnitude 0.0, Mercury will spend most of the month relatively close to Venus, and it will be only four degrees from Venus on the 13th. During the first two weeks of the month, it will be visible low over the eastern horizon, but it will reach maximum elongation from the Sun on the 14th. In good seeing conditions, Mercury and Venus will be visible less than 10 degrees above the eastern horizon around half an hour before dawn, but take care not to be caught unawares by the rising Sun if you are using optical aids.



Venus

Venus is now nearing its pre-dawn dominance of the sky. At the beginning of the month, Venus will rise just at the onset of twilight, but will rise progressively later until by month’s end, it will rise an hour or so before dawn. Since the relative angle between the ecliptic and the eastern horizon at the moment, Venus will be very low on the horizon. Nonetheless, it will be shining at magnitude -3.9, making it bright enough to be easily visible in good seeing conditions. Its magnitude will also remain constant during the month- although its angular diameter diminishes from 12 to 11 seconds of arc, its illumination will increase from 85- to 90%, thus maintain its brightness.

Mars

Mars continues its eastward motion through Libra, and by month’s end, it will have increased its brightness from +0.8 to +0.3 as its angular diameter increases from 6.8 to 8.6 seconds of arc. Look for Mars in the morning twilight before dawn when it is highest in the sky, and with a good telescope and even better seeing conditions, it might just be possible to discern the north polar ice-cap, and with some luck, even Syrtis Major. The Red Planet is currently moving into opposition with the earth on the 22nd of May, and by the 30th of May, it will be at its closest point to Earth. On this day Mars will have an angular diameter of 18.6 seconds of arc, and be almost as bright as Jupiter.

Jupiter

February is one of the best of the year to observe Jupiter, and now being in the southern parts of Leo, it will reach a culmination of about 45 degrees when it is due south. On the 8th of the month, Jupiter will be in opposition, and therefore be visible from latish evening to just before sunrise for much of the month. As Jupiter moves westwards through Leo, its angular diameter will increase slightly from 42 to 44 seconds of arc, which will marginally increase its brightness from magnitude -2.4 to -2.5. February offers excellent opportunities to observe the equatorial bands and the Great Red Spot, which is now close to the central meridian.

Saturn

Saturn is now a brilliant morning object, rising as it does at about 04:30 UT in the beginning of the month. By month’s end, it will rise as early as 03:00 UT, which is a good time to look for it 7.5 degrees above Antares, near the fan of Scorpius in Ophiuchus. The ring system has now opened up to about 26 degrees, and shining at magnitude +0.5, it will be hard to miss above the south-eastern horizon before sunrise, despite atmospheric interference. However, it never rises above 20 degrees over the horizon, which means that observers in far northern latitudes may not get to see the rings opened up as far as they ever get.

February Highlights

The Great Red Spot

About the only highlight to look forward to during February are the many opportunities that exist to observe the intricate detail in Jupiter’s cloud tops, and off course, the Great Red Spot that is particularly well placed just at the moment. The following list gives the best dates and times during the month at which to observe the major features on Jupiter: 2nd (20:11), 4th (21.48), 6th (23:36), 7th (19:18), 9th (20:56), 11th (22:33), 16th (21:40), 18th (23:18), 21st (20:47), 23rd (22:25), 28th (21:32).

Observe the Moon Occult a Star

On the 13th of the month, at about 19:20 UT, you may want to observe the Moon occulting xi 1 Ceti, a star of 4.4 magnitude, seeing conditions permitting of course. The occultation should be over by 20:19 UT when viewed from Manchester and surrounds, but be aware that the timings will be different for the rest of the UK.