Night sky guide for February 2016

February 2016 starts with the conjunction between the Moon and Mars. The pair will be located in the constellation Libra and visible to the naked eye or through a pair of binoculars on February 1.

The best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere – New Moon – falls on February 8. 

The Moon will reach full phase – making it visible for much of the night, lying almost directly opposite the Sun in the sky at 18:21 UTC on February 22.

• February 1 – Conjunction between the Moon and Mars – 10:10 UTC. The Moon and Mars will make a close approach, passing within 2°39' of each other. At the moment of closest approach, the Moon will be at mag -11.8, and Mars at mag 0.4, both in the constellation Libra. They will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.

• February 3 – Conjunction between the Moon and Saturn – 19:27 UTC. The Moon and Saturn will make a close approach, passing within 3°28' of each other. At the moment of closest approach, the Moon will be at mag -11.1, and Saturn at mag 1.2, both in the constellation Ophiuchus. The pair will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.

• February 7 – Mercury at greatest elongation west 03:30 UTC. Across much of the world, Mercury will be well placed for observation in the dawn sky, shining brightly at mag -1.9. Over the coming weeks, the distance between Mercury and the Sun will decrease each morning, and it will gradually sink back into the Sun's glare

• February 8 – New Moon – 14:40 UTC. The Moon will pass close to the Sun and become lost in the Sun's glare for a few days. The Moon's orbital motion carries it around the Earth once every four weeks, and, as a result, its phases cycle from new moon, through the first quarter, full moon and last quarter, back to the new moon once every 29.5 days. This motion also means that the Moon travels more than 12° across the sky from one night to the next, causing it to rise and set nearly an hour later each day. At new moon, the Earth, Moon and Sun all lie in a roughly straight line, with the Moon in the middle, appearing in front of the Sun's glare. In this configuration, we see almost exactly the opposite half of the Moon to that which is illuminated by the Sun, making it doubly unobservable because the side we see is almost entirely unilluminated. Over coming days, the Moon will become visible in the late afternoon and dusk sky as a waxing crescent, setting an hour later each evening. By the first quarter, in a week's time, it will be visible until around midnight. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.

• February 8 – NGC 2808 is well placed for observation. Across much of the world, the globular cluster NGC 2808 in Carina will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -64°52', it is easiest to see from the southern hemisphere and cannot be seen from latitudes much north of 5°N. At magnitude 6.3, NGC2808 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

• February 12 – Conjunction between the Moon and Uranus – 14:38 UTC. The Moon and Uranus will make a close approach, passing within 1°38' of each other. At the moment of closest approach, the Moon will be at mag -11.1, and Uranus at mag 5.9, both in the constellation Pisces. The pair will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.

• February 15 – Asteroid 5 Astraea at opposition – 14:39 UTC. Asteroid 5 Astraea will be well placed for observation, lying in the constellation Leo, well above the horizon for much of the night. Regardless of your location on the Earth, 5 Astraea will reach its highest point in the sky at around midnight local time. This optimal positioning occurs when it makes its closest approach to the point in the sky directly opposite to the Sun – an event termed opposition. Since the Sun reaches its greatest distance below the horizon at midnight, the point opposite to it is highest in the sky at the same time. At around the same time that 5 Astraea passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest in the night sky. This happens because when 5 Astraea lies opposite to the Sun in the night sky, the solar system is lined up so that 5 Astraea, the Earth and the Sun lie in a straight line with the Earth in the middle, on the same side of the Sun as 5 Astraea. On this occasion, 5 Astraea will pass within 1.098 AU of us, reaching a peak brightness of magnitude 8.6. Nonetheless, even at its brightest, 5 Astraea is a faint object beyond the reach of the naked eye or binoculars; a telescope of moderate aperture and a good star chart are needed.

• February 19 – M81 is well placed for observation. Bode's galaxy (M81, NGC 3031) in Ursa Major will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of +69°04', it is easiest to see from the northern hemisphere and cannot be seen from latitudes much south of 0°S. At magnitude 6.9, M81 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or small telescope.

• February 21 – NGC 3114 is well placed for observation. Across much of the world, the open star cluster NGC 3114 in Carina will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -60°07', it is easiest to see from the southern hemisphere and cannot be seen from latitudes much north of 9°N. At magnitude 4.2, NGC3114 is tricky to make out with the naked eye except from a dark site, but is visible through a pair of binoculars or a small telescope.

• February 22 – Full Moon – 18:21 UTC. The Moon will reach full phase – making it visible for much of the night, lying almost directly opposite the Sun in the sky. Full Moons are traditionally given names according to the season in which they fall, and this will be the third full moon of winter 2016, traditionally called the Lenten Moon. Over the nights following February 22, the Moon will rise around an hour later each day so as to become prominent later in the night. Within a few days, it will only be visible in the pre-dawn and early-morning sky. By the time it reaches last quarter, a week after full moon, it will rise at around midnight and set at around noon. At the moment when the Moon reaches full phase, it will lie at a declination of +08°44' in the constellation Leo, and so will appear high in the sky at all but the most extreme latitudes. It will be visible at all latitudes between 88°N and 71°S. Its distance from the Earth will be 397,000 km. This full moon was known by early Native American tribes as the Full Snow Moon because the heaviest snows usually fell during this time of the year. Since hunting is difficult, this moon has also been known by some tribes as the Full Hunger Moon, since the harsh weather made hunting difficult.

• February 24 – Conjunction between the Moon and Jupiter – 03:01 UTC. The Moon and Jupiter will make a close approach, passing within 1°36' of each other.At the moment of closest approach, the Moon will be at mag -12.6, and Jupiter at mag -2.5, both in the constellation Leo. The pair will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.

• February 27 – IC2581 is well placed. Across much of the world, the open star cluster IC 2581 in Carina will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -57°37', it is easiest to see from the southern hemisphere and cannot be seen from latitudes much north of 12°N. At magnitude 4.3, IC2581 is tricky to make out with the naked eye except from a dark site, but is visible through a pair of binoculars or a small telescope.

• February 28 – Neptune at solar conjunction – 15:49 UTC. From our vantage point on the Earth, Neptune will appear very close to the Sun in the sky as it passes around the far side of the solar system from the Earth. At closest approach, Neptune and the Sun will appear at a separation of only 0°47', making Neptune totally unobservable for several weeks while it is lost in the Sun's glare. At around the same time, Neptune will also be at its most distant from the Earth – receding to a distance of 30.95 AU – since the two planets will lie on opposite sides of the solar system. If Neptune could be observed at this time, it would appear at its smallest and faintest on account of its large distance. It would measure 2.2 arcsec in diameter. Over following weeks and months, Neptune will re-emerge to the west of the Sun, gradually becoming visible for ever-longer periods in the pre-dawn sky. After around six months, it will reach opposition, when it will be visible for virtually the whole night. A chart of the path of Neptune across the night sky can be found here, and a chart of its rising and setting times here.

• February 29 – Conjunction between the Moon and Mars – 19:39 UTC. The Moon and Mars will make a close approach, passing within 3°31' of each other. At the moment of closest approach, the Moon will be at mag -12.0, and Mars at mag -0.1, both in the constellation Libra. The pair will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.

Video courtesy Hubble Space Telescope

Sources: InTheSky (Dominic Ford), SeaSky

Featured image: Solar System Scope. Edit: TW.