The fainter stars of this asterism are part of the Hyades star cluster. Aldebaran, which lies some 90 light-years closer to us, is not.
Our final winter-sky asterism is Pakan’s 3 in the constellation Monoceros. You’ll find it about 3° southwest of the open cluster M50, or 2° north of 4th-magnitude Theta Canis Majoris. I have been able to identify this asterism through 18x50 binoculars, but a telescope will guarantee success.
The 11 stars of Pakan’s 3 range from magnitude 8.5 (SAO 133838) to magnitude 9.5 (SAO 152034). From top to bottom, it spans exactly 0.5°.
In the spring sky
The first vernal asterism that you should probably find is the Spring Triangle, a giant figure pulled straight out of a geometry class. It’s visible in the Northern Hemisphere all through spring, and three bright stars make up its points.
First is Arcturus (Alpha Boötis), the brightest star in the northern sky and fourth-brightest overall. It shines with an orange hue at magnitude –0.04. From Arcturus, move to sapphire-blue Spica (Alpha Virginis), which represents a sheaf of grain (probably wheat) in Virgo the Maiden’s hand.
Spica varies in brightness between magnitude 0.92 and 1.04, with a period of a bit more than four days. Finally, complete the Spring Triangle with Denebola (Beta Leonis), the tail of Leo the Lion. Denebola, at magnitude 2.1, is the sky’s 59th-brightest star, which is fairly notable considering human eyes can detect roughly 6,000 stars.
Next up is the Head of Hydra, which lies on the western end of the sky’s largest constellation. To find it, look 2° south of the midpoint of a line that joins Procyon (Alpha Canis Minoris) and Regulus (Alpha Leonis).
Six stars form this asterism. The brightest is magnitude 3.1 Zeta Hydrae. From there, move west to Epsilon and Delta Hydrae. Then, swing back east to Rho (ρ) Hydrae. Drop 3.5° southwest to Sigma (σ) Hydrae. At magnitude 4.4, this is the faintest star in the asterism. Head east again to the sixth and final star, Eta Hydrae, then finish the figure by returning to Zeta.
Now turn your gaze a third of the way across the sky to the north. There, through binoculars, you’ll find the Broken Engagement Ring. It lies 1.5° west of Merak (Beta Ursae Majoris), one of the Pointer stars of the Big Dipper.
The Ring’s brightest star, SAO 27788, which glows at magnitude 7.5, lies at its northern end. It’s the diamond in the ring. Unfortunately, the other stars, which lie south and west, don’t give off that much light. The second-brightest glows at magnitude 9.1, and the faintest is magnitude 9.9, which makes it only one-ninth as bright as SAO 27788.
The Broken Engagement Ring isn’t tiny. It spans 16', which is half the diameter of the Full Moon. The best views will be through 10x or higher binoculars, or through telescopes with eyepieces that provide a field of view a bit wider than a quarter degree.
Our next spring sky asterism, the Y of Virgo, ranks as the largest in a single constellation — but just barely. Its longest dimension beats that of the Big Dipper by 1°. The Y contains six stars, and they all have common names, which indicates that they’re fairly bright. Indeed, the faintest glows at magnitude 3.9.
But we begin the Y at its bottom with its brightest star, Spica (Alpha Virginis), a blue-white sparkler. From it, move 15° northwest to Porrima (Gamma Vir). There, the Y branches in two directions, toward the north-northeast and the west-northwest. The north-northeast leg contains Minelauva (Delta Vir) and Vindemiatrix (Epsilon Vir). The west-northwest branch contains Zaniah (Eta Vir) and Zavijava (Beta Vir).
Moving from the very large to the very small, point your telescope 12° due west of Spica to find the Stargate in the constellation Corvus. It lies midway between Delta Corvi and Chi (χ) Virginis, and it consists of two triangles of stars, one within the other. The outer one measures roughly 5' on a side, while the sides of the small one each span less than 1'.
You can spot the outer triangle through binoculars — well, two of its stars, at least. They glow at magnitudes 6.6 and 6.7, and the third is much fainter, at magnitude 9.9. The three inner stars are more subtle: magnitudes 8.0, 9.7, and 10.6. The best views come through a 4-inch or larger scope with an eyepiece that gives a magnification of about 50x.