The full beauty of the brilliant stars in the winter hexagon become evident in January, as the entire group is well above the southeastern horizon and perfectly placed for viewing by 8 p.m. Although they may look somewhat alike at first glance, the eight stars tell unique and astounding stories.
Beginning at the top of this hexagon, you will see Capella in Auriga. Proceed clockwise to Aldebaran in Taurus, an orange giant star 65 light years away whose name in Arabic means “the follower,” since it appears to follow the Pleiades through the sky.
Continue on to Rigel, marking the left knee of Orion the Hunter. This is a blue super giant star 800 light years away that is 17 times the mass of our sun and 85,000 times as luminous. Then you will see the lowest star in this group and also the brightest in the whole sky, Sirius in Canis Major. It is one of the closest stars to earth at only 8 light years away. Then proceed up the left side to Procyon in Canis Minor and finish the circle with Castor and Pollux in Gemini. Both Castor and Pollux, the mortal and immortal twins in Greek mythology, are actually multiple star systems.
Near the middle of this hexagon, sometimes also called the Winter Circle or Heavenly G, is the red supergiant star named Betelgeuse. This one is by far the most amazing and exciting star in the whole group.
It varies a full magnitude in brightness and it is the first star other than our sun on which we have seen an extended disk and sunspots, even though it is located about 700 light years away. That is because this star is so huge, fully 1,000 times the radius of our sun.
To appreciate this size, make the earth a tiny pearl one millimeter across and our sun the size of a mango, 100 times larger than Earth. Then Sirius would be a soccer ball and Betelgeuse would be the size of the entire football stadium, making it one of the largest stars in our whole Milky Way galaxy of over 200 billion stars.
Even though Betelgeuse is young, only about 10 million years old, this voracious star has already burned through almost all of its fuel. It exhausted its hydrogen long ago and is now fusing helium into carbon and oxygen. It will soon be fusing heavier elements, including neon, magnesium, sodium and silicon, all the way up to iron, after which it will collapse and explode as a type II supernova.
Betelgeuse could be one of only a handful of stars that may have already exploded, or it may take another few thousand years. The reason these huge stars have to burn through their prodigious amounts of fuel so quickly is to maintain their perfect gravitational balance of the weight of all the gas pressing inward with the fusion forces pushing outward as they consume and transform all this gas.
Once it explodes as a cataclysmic supernova, all of these newly forged elements get released back into our galaxy as the ultimate recycling process. These elements get swept up by massive density waves continually pulsing through our galaxy, turning all this material back into new stars and planets, and in at least one case and probably many more, into plants and animals and humans. We are more powerfully linked to the stars than we can imagine.
SLIGHT CHANCE TO SEE METEORS
The other highlights for this first month of the year include another meteor shower, Jupiter still gracing our evening sky, and Saturn and Venus adorning our morning sky.
The Quadrantid Meteor shower will peak around 1 a.m. on Jan. 4. You could start looking around 9 p.m. on Jan. 3 to catch a few “earth grazers” that skim along our upper atmosphere. The moon will not interfere, so we might get lucky and see up to 60 meteors per hour. However, this peak is very narrow and is not perfectly placed for us in the Northeast, because the constellation from which these meteors will appear to originate, Bootes, will not be above the horizon yet.
Just like the Geminids last month, these meteors are also caused by an asteroid. Named EH1, this was probably a piece of a comet that broke off about 500 years ago.
The peak of this shower is so short because our orbit intersects this comet debris at a perpendicular angle. The weather also tends to be stormy this time of year, so it is hard to catch many of these elusive meteors. Even if it is cloudy, you can at least hear these meteors on space weather radio. Air Force Space Surveillance Radar allows us to hear the pings caused by the powerful transmitter echoing off the ion trail of a meteor.
Jupiter is the only bright planet in our evening sky. It begins the month setting at 11 p.m., but it sets by 9:30 p.m. by the end of the month. Through a telescope you will see that the lost South Equatorial Band is returning. Watch the waxing crescent moon on the evenings of Jan. 8 through Jan. 10.
Saturn and Venus are both shining brightly in our morning sky. At magnitude minus 4.6, Venus is just over 100 times brighter than Saturn. The ringed planet begins the year by rising at 12:30 a.m., and by the end of the month it will be rising two hours earlier.
Saturn is now at quadrature, 90 degrees west of the sun, so the shadows of the planet and its rings fall farthest to the side, which improves its three-dimensional appearance. Through a telescope you will also notice that its rings are now tilted 10 degrees from edge-on, which is the widest they have been since 2007.
Venus is now at its highest in the sky, so it will rise almost four hours before the sun and climb to 20 degrees above the southeastern horizon in Sagittarius while the sky is still fully dark. Through a telescope, notice that this brilliant planet is now half illuminated by the sun, similar to a first quarter moon.
Mercury also makes a good appearance in the morning sky, visible all month long well to the left and below Venus in the morning sky one hour before sunrise. It is about 80 times fainter than Venus.
Watch the slender waning crescent moon pass near the pair on the first two mornings of this year.
Jan. 1: On this day in 1801, Piazzi discovered the first and largest asteroid, named Ceres. It is about 600 miles in diameter and would have to be reclassified as a planet if Pluto were still a planet.
Jan. 3: The Quadrantid Meteor shower begins tonight. Earth reaches perihelion, its closest point to the sun in its annual orbit, around 2 p.m. today. We will be 91,407,000 miles away, or 1.7 percent less than the average of 93 million miles. Along with the new moon, this will cause higher high tides and lower low tides than normal.
Jan. 4: New moon is at 4:03 a.m. EST. There will be a partial solar eclipse today visible over most of Europe and parts of Africa and Asia.
Jan. 12: First quarter moon is at 6:31 a.m.
Jan. 19: Full moon is at 4:21 p.m. This is known as the snow moon or the moon after yule.
Jan. 25: The waning gibbous moon is to the right of Saturn and Spica, forming a triangle with them around 1 a.m.
Jan. 26: Last quarter moon is at 7:57 a.m.
Jan. 28-30: The waning crescent moon is near Venus and Antares in the morning sky one hour before sunrise.
Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.