Russell Eberst's Sky View

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January 2018

The astronomical New Year begins with a Full moon, meteor shower and the Earth at perihelion, all in the space of the first four days. The closest that the Earth comes to the Sun each year occurs in early January, this year on January 3 at 05.35 U.T. Despite receiving more than 3 percent extra radiation than average, this bonus is more than outweighed in the northern hemisphere, by the fact that the Earth's axis is tilted so the north will experience its coldest period of the year. However the resulting long nights should provide some opportunity to study the glorious constellations of winter. The night of January 3/4 brings the annual display of the Quadrantid meteor shower, which radiates from the northern part of the constellation of Bootes, the herdsman. This is not far from the last star in the tail of the Great Bear (eta Ursa Major). The constellation from which the shower derives its name, Quadrans, no longer exists. It represents an ancient astronomical instrument used for measuring angles, called a quadrant. Although Quadrans failed to make it into the definitive list of constellations, it is recalled by the name of this shower. Many members of this shower will be missed due to the overpowering brightness of the Moon. This reaches Full phase on January 2 at 02.24 U.T. Earlier the same night the Moon reaches a close perigee, resulting in a larger disc for Earth-based observers. Undoubtedly the media will latch on to this event, and the word "Supermoon" is likely to appear frequently. Observing this large Full Moon can be enhanced by watching it when it's near the horizon so that the "Moon Illusion" come into play. The next Full Moon at the end of January will bring another deluge of Supermoon references, but this time it will also involve the colours 'Blue' and 'Red'. When there is a second Full Moon in a calendar month, the second one is often termed a 'Blue' Moon. On January 31, the Full Moon therefore qualifies as a 'Blue' Moon, but will take on a very different hue.

During the last day of the month, the Moon will pass through the Earth's shadow and thereby suffer a total eclipse. Totality lasts from 12.52 to 14.08 U.T. From the U.K. the Moon will be well below the horizon, so that no stage of the eclipse will be visible from this part of the world. Those around the Pacific Rim will be much better placed to view 76 minutes of totality. During this period, the Moon will appear a coppery-red as sunlight, reddened and refracted by the Earth's atmosphere falls on the lunar disc. For British observers, we will have to wait until July for a chance to see a total lunar eclipse. Meanwhile, we must content ourselves with improving views of the Moon and planets. The Moon, having occulted Aldebaran on the morning of December 31, goes on to cover Regulus. This is the brightest star in the constellation of Leo, but once again this is a daylight event, and it will take a large telescope to see the star disappear behind the Moon at around 8.16 a.m. U.T. on January 5. Two mornings later on January 7 there is a splendid conjunction of the bright planets Jupiter and Mars. These can be found low in the south-east in the pre-dawn sky. The pair will be less than 0°.25 apart, or half the apparent size of the lunar disc. Jupiter is the northern of the two and about 18 times brighter than Mars, despite being more than three times further away. They are located in the constellation of Libra, the scales. Its leading star is Zubenelgenubi which will be 2°.5 to the west of the conjoined pair. Thereafter Mars continues to speed to the East in the general direction of Antares, its 'rival'. Jupiter plods much more slowly and will remain in Libra for much of the rest of the year. The decrescent Moon joins the separating pair on the morning of January 11 to provide an appealing scene and a great opportunity for astrophotographers to capture an unusual sight.

With all this activity in the morning sky, there is comparatively few targets for those that confine their observing to the evening hours. Fortunately there is an object that will keep our attention throughout the month. It is the variable star known as Mira. Mira displays huge variations in its brightness. Its variations were first reported by David Fabricius (real name: Goldschmid) towards the end of the 16th century. It was named 'Mira' meaning "wonderful" by Helvelius in 1662. The more prosaic designations are omicron Ceti, or 68 Ceti, since it is located in the constellation of Cetus, the Sea monster (known locally as "Nessie"). Mira can be found in the long neck of the monster. Its head is defined by the stars alpha, gamma and delta Ceti, and we can use these to find Mira. Taking a line from alpha to delta (some 7° apart) and then going a further 6° in the same direction, we reach the area that contains Mira. This star varies in brightness by a factor around 1000, from magnitude +10 when at minimum, to possibly magnitude +2.5 at max. over a period of about 11 months. So from requiring a reasonably sized telescope to becoming easily visible to the unaided eye. However, both the interval between maxima, and the maximum that the brightness attains are slightly variable. Therefore it needs regular monitoring, and predictions of its future magnitudes are not easily estimated. The next peak in magnitude is expected during January 2018, and its progress will be watched globally. To end on a personal note, January 22 will see the 60th anniversary of my first sighting of an Earth satellite. On that date in 1958, I spotted Sputnik 2 on two consecutive passes and that set me on an activity that has enthralled me ever since.

Moon phases:

  • Full Moon: January 3 & 31
  • Last Quarter: January 8
  • New Moon: January 17
  • First Quarter: January 24

Sky View Image

The maps show the sky at 21:00 GMT on the 1st, 20:00 on the 16th and 19:00 on the 31st