Twice in a blue moon in 2018
Mercury and Saturn appear low in the early dawn sky this month
The full moon of Jan. 1 was the first full moon of January and of the year.
It was also the largest full moon of the year, due to the fact that the moon’s perigee (its closest approach to Earth) occurred approximately four and a half hours before the moon reached its full phase.
That supermoon was the largest and brightest of 2018. It was also the second of three consecutive supermoons, the first having occurred on Dec. 3, 2017. The third supermoon will occur on Jan. 31. There will be 12 other full moons and 13 additional lunar perigees throughout 2018.
January has two full supermoons, the second of which occurs on Jan. 31. When two full moons occur within one calendar month, the second full moon is termed a blue moon. The moon will not, however, actually appear blue in colour. By this definition, there will also be a blue moon on March 31, while the next one won’t occur until Oct. 31, 2020.
However, this is not the only definition of a blue moon. Normally, there are three full moons in a season (winter, spring, etc.) calculated as the period between a solstice and an equinox or between an equinox and a solstice. If there are four full moons within a season, then the third full moon is termed a blue moon. Based on this definition, the next seasonal blue moon will occur on May 19, 2019.
This month, Mercury and Saturn appear low in the ESE in the early dawn sky. Mercury (in Serpens Cauda - the Serpent’s Tail) will become visible in the first half of the month, joined by Saturn (in Sagittarius - the Centaur) during the second half.
They will pass each other on the morning of Jan. 13. Binoculars will help pick them out of the increasing glow of the rising sun.
Likewise, Jupiter and Mars
rise in the early morning hours, appearing high in the SE sky at dawn in the constellation of Libra - the Scales. Look for them fairly close to one another approximately two and a half hand’s width (at arm’s length) above the SE horizon about one hour before sunrise.
Look for bright Jupiter below the waning crescent moon on the morning of Jan. 10 and to the right of a thinner crescent moon on Jan. 11. Ruddy-coloured Mars will sit just to the lower left of Jupiter. Do not confuse Mars with the reddish star, Antares (the “Rival of Mars”) in the constellation of Scorpius the Scorpion lower to the left and closer to the horizon.
Though the peak actually occurred this morning (Jan. 3), there may still be some Quadrantid meteors around on the morning of Jan. 4. The radiant for this meteor shower, with a peak zenith (directly overhead) rate of 60-100 meteors per hour, is located in the constellation of Bootes - the Herdsman. This constellation is highest in the southern sky in the pre-dawn hours.
As with all meteors showers, this is the best time to view them. Meteor showers are notoriously fickle, and numbers can vary enormously, not only from hour to hour, but also from one night/pre-dawn to another, so, if the weather permits, it might be well worth it to step outside for a few minutes on the morning of Jan. 4; you might be pleasantly surprised.
Until next month, clear skies, and all the best for 2018.