The Night’s Bright Lightstesttest
As if to hammer another nail into summer’s coffin, the sun this week sets before 7:00. The darkening sky reveals Venus tight above the southwest horizon, and while the evening star is brilliant at magnitude –4, it, too, is fleeting and sets shortly after the sun.
As the sun and Venus set in the west, Jupiter rises in the east. Last week this gaseous giant reached opposition — its point opposite the sun as seen from our earthbound vantage — and so rises with sunset and sets with daybreak. The second-brightest stellar object other than the sun and moon, Jupiter shines even brighter than usual as it passes its closest to earth since 1963. At 368 million miles, that’s only a one or two percent difference, but it’s noticeable and won’t appear so bright for a dozen years.
While there should be no mistaking Jupiter, the giant planet this week appears just one degree below distant Uranus. Five times farther away and a couple thousand times brighter than Jupiter, Uranus can’t be seen with the unaided eye. But with binoculars it looks like a faint star, while with even a small telescope you should be able to discern its green-hued disc.
Jupiter and Uranus are low in the west before sunrise, around 7am this week. In the half-hour before dawn, however, Mercury rises in the east. Mercury never strays far from the sun’s overpowering glare. But for the next week, this fleet planet makes its best pre-dawn appearance of the year. Mercury is surprisingly bright and easily visible to the unaided eye. But it is so low in the sky that you may want to scan the eastern horizon with binoculars to spot it. Don’t confuse Mercury’s steady glow for twinkling blueish Regulus a dozen degrees higher. Each day Mercury slips a degree closer to the horizon, but — nearing the sun in the process — it shines all the brighter.