Northern Cross
The stars offer a holiday decoration this evening: the Northern Cross, which is also known as Cygnus, the swan. Its brightest stars form the shape of a cross, which is in the west and northwest at nightfall.
Moon and Jupiter
Jupiter is close to the right of the gibbous Moon as darkness falls tonight. It looks like a brilliant star, although it’s really the largest planet in the solar system, at roughly 11 times Earth’s diameter.
Cat’s Eye Nebula
The Cat’s Eye Nebula — a glowing bubble of gas expelled by a dying star — is several thousand light-years away, in Draco, the dragon. The nebula is in the north-northwest at nightfall. Seen through a telescope or in images, it does resemble a glowing cat’s eye.
Winter Solstice
Winter arrives in the northern hemisphere tomorrow night. That’s the time of the winter solstice. Tomorrow and Friday will be the shortest days of the year in the northern hemisphere. The Sun will rise farthest south for the year as well.
First Quarter
The Moon reaches its first quarter phase today as it lines up at a right angle to the line between Earth and the Sun. Sunlight illuminates half of the hemisphere that faces our way, so it looks like the Moon has been sliced down the middle.
Sextans
The faint constellation Sextans, the sextant, climbs into view by midnight, to the lower right of the bright star Regulus, the heart of the lion. The constellation lies along the celestial equator, which is the projection of Earth’s equator on the sky.
Moon and Saturn
Saturn is in great view tonight. The solar system’s second-largest planet looks like a bright star quite close to the Moon. They set in late evening. Saturn will appear much farther to the lower right of the Moon tomorrow night.
Shielding Orion
Orion’s shield leads the hunter across the sky. To find it, line up bright orange Betelgeuse, low in the east, and slightly fainter Bellatrix, to its upper right. The shield is farther along that line, marked by its brightest star, Tabit.
Gomeisa
Gomeisa, the second-brightest star of Canis Minor, the little dog, is quite low in the east by about 9 p.m. It’s above Procyon, the constellation’s brightest star. Gomeisa is several times the size and mass of the Sun.
Mirzam
Sirius, the brightest star in the night, rises in the southeast in mid-evening. A star close to its right or upper right looks fainter, but really is thousands of times brighter. Mirzam looks fainter than Sirius because it’s about 500 light-years farther.