January 2018

Welcome to SkyEye, your guide to this month's celestial events.

The Calendar

Date Body Event
1 Mercury greatest elongation west
Moon closest perigee of the year
2 Moon full
Uranus stationary - retrograde to direct
3 Earth Quadrantid meteor shower
Earth perihelion
5 Moon occultation of Regulus: visible from Alaska, northern Canada, Greenland, Iceland, western Europe and northwestern Africa
7 Mars, Jupiter 0.2° apart
8 Moon last quarter
9 Venus superior conjunction
13 Mercury, Saturn 0.6° apart
14 Uranus east quadrature
15 Moon farthest apogee of the year
17 Moon new
20 Moon, Neptune 1.6° apart
23 Venus aphelion
24 Moon first quarter
25 Mercury aphelion
27 Moon occultation of Aldebaran: visible from most of Asia and northwestern North America
30 Moon perigee
31 1 Ceres opposition
Moon total lunar eclipse
Moon full

The Solar System

The word planet is derived from the Greek word for 'wanderer'. Unlike the background stars, planets seem to move around the sky, keeping mostly to a narrow track called the ecliptic, the path of the Sun across the stars. Dwarf planets and small solar-system bodies, including comets, are not so constrained, often moving far above or below the ecliptic.

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Sun SagittariusCapricornus

Mercury OphiuchusSagittariusCapricornus

Mercury is at greatest elongation west on the first day of the year, placing it in the morning sky. It is barely visible from northern latitudes but is more easily seen from the equatorial regions and southern hemisphere. It passes within a degree of Saturn on 13 January.

Venus SagittariusCapricornus

At superior conjunction on 9 January, the brightest of all the planets is too close to the Sun to be observed this month. It takes its place as the evening star in the west next month.

Earth and Moon

The Earth makes its annual closest approach to the Sun on 3 January. The date of perihelion can range from New Year's Day to 5 January and often coincides with the peak of the Quadrantid meteor shower. Unfortunately, this year apparition is washed out by bright moonlight.

The Moon has a particularly busy month. Less than five hours separate perigee and Full Moon which results in a so-called 'Super Moon' on the second day of the month. Expect perigean spring tides. Another Full Moon occurs on 31 January. The second such occurence in a calendar month is popularly called a Blue Moon. This Blue Moon is unusual in that it will undergo a total lunar eclipse.

This month also sees both the closest perigee of the year and the farthest apogee of the year. The Moon occults two first-magnitude stars, Regulus on 5 January and Aldebaran on 27 January, and sails by the planet Neptune on 20 January.

Mars LibraScorpius

The red planet is a morning sky object this month. On 7 January, it has a very close encounter with another outer planet, Jupiter, passing less than half a degree away from the brighter object. Look for both planets in the east before sunrise. Currently located south of the celestial equator, Mars is best viewed from southern latitudes.

1 Ceres LeoCancer

The largest body in the main asteroid belt reaches opposition on the last day of the month. Ceres shines at magnitude +6.9, making binoculars or a small telescope necessary for seeing it.

Jupiter Libra

Jupiter rises ahead of the Sun so you'll need to get up early to see it. The largest planet in the solar system makes a spectacular pre-dawn pairing with Mars on 7 January. Like the red planet, Jupiter is most easily seen from the southern hemisphere.

Saturn Sagittarius

At solar conjunction late last month, Saturn is still quite close to the Sun but is slowly pulling away. It appears near Mercury on 13 January in the morning twilight.

Uranus Pisces

This ice giant begins the year in retrograde but reaches a stationary point on the second day of the month and then resumes direct motion. It is at east quadrature on 14 January and sets around midnight.

Neptune Aquarius

A small telescope is necessary to view the most distant planet in the solar system. However, with solar conjunction approaching in early March, it is getting increasingly difficult to observe. Look for it in the west as soon as the sky darkens. The waxing crescent Moon passes within 2° of Neptune on 20 January.

The Celestial Sphere

Constellations are patterns of stars in the sky. The International Astronomical Union recognises 88 different constellations. The brightest stars as seen from the Earth are easy to spot but do you know their proper names? With a set of binoculars you can look for fainter objects such as nebulae and galaxies and star clusters or some of the closest stars to the Sun.

Descriptions of the sky for observers in both the northern and southern hemispheres are available for the following times this month. Subtract one hour from your local time if summer (daylight savings) time is in effect.

Local Time Mid-month Northern Hemisphere Equator Southern Hemisphere
1730 hours (1830 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
1930 hours (2030 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
2130 hours (2230 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
2330 hours (0030 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
0130 hours (0230 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
0330 hours (0430 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S
0530 hours (0630 hours summer time) 60° N 50° N 40° N 30° N 20° N 10° N 10° S 20° S 30° S 40° S