Stars over Sisters
Last updated 5/5/2023 at 4:58pm
Though not to be feared, the head of a dragon does appear high in the northeast sky during the evening hours of May. Known as Draco, this celestial reptile is the eighth largest constellation by area. The tip of its tail lies between the cup of the Big Dipper and Polaris (the North Star) while its body passes between the two dippers and circles halfway around the Little Dipper. The beast's head then turns back on its body, positioned just north of the constellation of Hercules.
Draco is one of the Greek constellations, first catalogued by astronomer Ptolemy in the second century. It is a circumpolar constellation from our latitude, never setting below the horizon.
Draco's brightest star is Eltanin (Arabic for Dragon Head), which shines at a magnitude of 2.2. It is an orange-colored giant star approximately 1.7 times more massive than the sun located at a distance of 154 light-years. Astronomers have estimated that in about 1.5 million years from now, Eltanin will approach within 28 light-years of the sun, and become the brightest star in the sky.
Although it is only the eighth brightest star in Draco, Thuban holds special historical significance in that it served as the Pole Star from 3942 BCE to 1793 BCE, due to the precession of earth's axis of rotation.
In 2022 a team of scientists discovered an exoplanet orbiting a binary system in Draco that is only 100 light-years away. It is slightly larger than our earth and is located at a distance from its star where temperatures could allow for liquid water to exist on its surface.
While Draco contains a large collection of deep-sky objects, all but one of them are galaxies. Three of the most well-known of these have been dubbed the Spindle Galaxy (NGC 5866), the Knife Edge Galaxy (NGC 5907), and the Tadpole Galaxy (Arp 188) because of their distinctive shapes. The lone exception to these far-flung galaxies is a much nearer planetary nebula.
NGC 6543, nicknamed the "Cat's Eye Nebula," is one of the most complex planetary nebulae ever seen. The Hubble Space Telescope has revealed intricate structures, including concentric gas shells, jets of high-speed gas, and unusual shock-induced knots of gas. Estimated to be just 1,000 years old, this object is only 3,300 light-years away.
Probably the most common myth associated with Draco describes a golden apple tree gifted to Hera when she married Zeus. The goddess planted the tree in her garden on Mount Atlas, tasking Atlas' daughters and the dragon Ladon with guarding it. However, as part of his twelve labours, Heracles was asked to steal some golden apples from the tree. So he slew Ladon with poisoned arrows and took the apples. Saddened by the dragon's demise, Hera placed its image among the stars.
The Eta Aquariids meteor shower is expected to peak between May 4-5 of the month with up to 50 shooting stars per hour. That's the good news. The bad news is that excessive glare from the Full Flower Moon will hide all but the brightest of these. In addition, the radiant is in the constellation of Aquarius, which for us doesn't rise until well after midnight and stays low on the horizon.
Venus will put on its best display of the year this month as the brilliant orb moves out of Taurus into Gemini. Although much dimmer, Mars is also nearby, crossing into Cancer by mid-month. Look for both these planets low in the western sky after sunset.
On the morning stage, Saturn continues to pull away from the sun, rising at 1:30 a.m. local time on May 31. By the latter third of the month, Jupiter and Mercury will join the Ringed Jewel, both emerging from the sun's glare.
The dark-sky tip for this month is to turn your outdoor lights off when they are not in use. Consider turning them off a few hours after sunset or before you go to bed. A good way to make sure the lights go out is to put them on timers.