All Lined Up Along the Ecliptic
Sirius the Dog Star, blazes high in the south by 10pm. The brightest star, Sirius is easy to spot, but if you have any trouble, follow the three belt stars of familiar Orion down and to the left.
Last week we traveled the Great Winter Circle, which encompasses Sirius. The Dog Star also anchors another asterism, the Winter Triangle. The other two points are Betelgeuse, marking Orion’s upper shoulder, and Procyon, the Little Dog in Canis Minor, which together with Sirius, the lowest of the three, form a near-perfect equilateral triangle.
For the first time since 2005, all five naked-eye planets are visible, aligned on the arc of the ecliptic before dawn. This week they are joined by the moon, as well.
Jupiter leads the way. Old Jove in fact rises due east a little after 9pm and as dawn approaches is high in the west-southwest. Friday you’ll find the moon midway between Jupiter and Spica, the first-magnitude star of Virgo. Then Saturday the moon is less than two degrees to the upper left of Spica.
To the east of Spica is Mars, which rises around 1am. Sunday before dawn the last-quarter moon is midway between Spica and Mars. Early Monday morning, the moon is just a few degrees to the upper left of Mars. Keep an eye on the red planet, as it draws closer to earth — and brighter — over the coming months.
Saturn is next in line, rising in the east-southeast after 3:30am. Before dawn Tuesday the moon is between Saturn to the east and Mars to the west. Wednesday the ringed planet is just a few degrees beneath the waning crescent moon.
Venus rises in the southeast around 5:30am, and once it’s crested the horizon there should be no mistaking this morning star, which is brighter than all but the sun and moon.
The last planet, Mercury, is another matter, rising in the southeast amid the gathering glow of dawn. While brighter than most stars, the innermost planet is so tight against the horizon that you’ll have an easier time spotting it with binoculars. This week Mercury is within 10 degrees of Venus but will close the gap in the coming week, climbing higher and growing brighter before daybreak.