This looping animation depicts the naked-eye view to the south-southeast as seen from the heart of the British Isles at 7:15am GMT from 4 to 14 January 2018. Mercury, the Solar System’s innermost planet, is visible very close to the southeast horizon until about 10 January for UK observers. Mars passes just 12 arcminutes (one-fifth of a degree) south of Jupiter on 7 January, and the 24-day-old waning crescent Moon joins the planetary pair for a glorious conjunction in the southern sky on 11 January. Note that the Moon’s size is slightly enlarged for clarity. AN graphic by Ade Ashford.It currently pays to be an early riser if you wish to view the planets, for it’s all happening at dawn in the skies of Western Europe. Observers in the UK wishing to get the best views should find a location that offers an unobstructed southeasterly aspect where, if you are blessed with clear skies between 7am GMT and sunrise, you could see Mercury, Mars and Jupiter in addition to a waning Moon.
Jupiter is the bright magnitude -1.8 ‘star’ in the constellation of Libra currently visible in the south-southeast around 7am GMT. Look carefully at the Solar System’s largest planet over the next few mornings and you’ll notice another celestial body closing in on it: Mars. At magnitude +1.4, the Red Planet is presently nineteen times fainter than Jupiter.
In the UK dawn twilight of Thursday, 11 January, Mars and Jupiter lie 2 degrees apart. In this simulated 10×50 binocular field of view, you’ll also fit in the 24-day-old waning crescent Moon. With higher magnification binoculars and small telescopes, you’ll also see all four of Jupiter’s Galilean moons strung out in a line on one side of the planet. In order of separation from Jupiter they are Io, Europa, Ganymede and Callisto — on this occasion matching the arrangement of their orbits about the largest planet. Click the graphic for a full size version. AN graphic by Ade Ashford.Mars passes just 12 arcminutes (that’s one-fifth of a degree, or 40 percent of the full Moon’s diameter) south of its larger planetary sibling in the small hours of Sunday, 7 January. By civil dawn in the British Isles that day the gap between the pair will have widened to 14½ arcminutes, or slightly less than half the apparent size of the full Moon. Don’t miss Jupiter and Mars in the same telescope field of view at magnifications up to about 175x!
While the gap between Mars and Jupiter widens after 7 January, keep your eye on the waning lunar crescent. The 24-day-old Moon joins the planetary pair for a glorious conjunction in the southern sky on Thursday, 11 January. The conjunction is so close that owners of binoculars magnifying up to 10x will have no difficulty seeing the trio in the same field of view, but it will still look fabulous with the naked eye.
NASA’s Cassini spacecraft has observed geysers erupting on Saturn’s icy moon Enceladus since 2005, but the process that drives and sustains these eruptions has remained a mystery. Now, scientists have pinpointed a mechanism by which cyclical tidal stresses exerted by Saturn can drive Enceladus’s long-lived eruptions.
While looking for Geminid meteors, observers in Western Europe should also look to the southeast about 90 minutes before sunrise to see a beautiful conjunction of a 25-day-old Moon, Jupiter and Mars on Thursday, 14 December.
For an early astronomical treat to usher in the New Year, seek out the natural pyrotechnics of the rich Quadrantid meteor shower. Peak shooting star activity occurs within a four-hour window centred on a prediction of 8am GMT on 4 January 2020 – a time that favours UK skywatchers at astronomical dawn, or North American observers around local midnight.
