Celestial Greetings Fellow StarGazers!
Another week in social lockdown has come and gone. Hopefully, many of you have ventured outside to journey among the stars using our StarGazing Guides. Since those Guides are still pertinent for the next couple weeks, we opted to share some more astronomy fun facts.
One of the first questions we ask folks who attend our Bare Dark Sky Observatory events: “Can anyone name the planets in our Solar System from the Sun out to the Kuiper Belt?” There are almost always a few who correctly answer: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Some people remember the planets using a mnemonic device, such as: “My Very Energetic Mother Just Served Us Nine Pizzas,” which includes Pizza for Pluto. However, as most of you know Pluto got reclassified in 2006 as a dwarf planet. And why was that?
Why Pluto is Now a Dwarf Planet
In a nutshell, back in 2005 a larger-than-Pluto rock mass with a moon was discovered out beyond Pluto. It was named Eris and at first it was informally considered as our 10th planet. The following year, due to concerns that we would continue to discover more and more planets, the International Astronomical Union (IAU) issued a new definition of “planet” that requires the following three criteria: 1) orbit the Sun; 2) be a sufficient size revolving mass with nearly a round shape; and 3) clear the neighborhood in its orbit. It’s this “clearing” rule that got Pluto and Eris demoted to dwarf planet and has angered so many professional and amateur astronomers. After all, how can Pluto be accused of “not clearing its neighborhood” when it has five moons? Pluto however shares its orbit with many large objects in the Kuiper belt and so it has not cleared its neighborhood to nearly the extent of the other planets. But mostly, the dissatisfaction is because the IAU used vague wording and never specified any specific numbers or formulas for determining if something has “cleared its neighborhood.” And so the Pluto debate continues. By the way, we don’t think Pluto knows it’s not a planet.
Charles Messier
We promised back in our second Guide that we would talk about the famous French astronomer Charles Messier. Those of you who have visited BDSO have heard us refer to M13 (Hercules Cluster), M31 (Andromeda Galaxy), M42 (Orion Nebula), M45 (Pleiades) and dozens of other popular Messier (M) objects.
Messier started out as a comet hunter in the 1750s and over the next several decades discovered 13 comets, though he is often credited with 21. During his nightly searches for these spectacular moving bodies of ice, rock and dust, he kept documenting more and more objects that
remained constant
in the night sky. He kept a journal of these star clusters, galaxies, double stars, and nebulae so that they would not be confused with comets, and he gladly shared them with other astronomers. Over his lifetime Messier compiled 103 deep sky objects. Since his death in 1817, another 7 objects have been credited to him.
The Messier Catalog is a valuable tool that most amateur astronomers and astrophotographers utilize during their nightly adventures. In fact, every year between late March and early April, groups of stargazers conduct Messier Marathons in highly ambitious attempts to find all 110 Messier objects in only one night. Not an easy objective! As a final bit of trivia, Messier received a medal from Napoleon Bonaparte, and he was nicknamed “the ferret of comets” by King Louis XV for elevating France as the crème de la crème in astronomy.
Maximizing Your Night Sky Experience
In our SG Guides and at our observatory, we stress the importance of avoiding any bright light while you’re stargazing. No matter how advanced a telescope and its eyepieces, if your eyes are not fully accustomed to the dark, you won’t see much. You will achieve a large portion of your night vision within 5 to 10 minutes after twilight. At this point most people think this is as good as it gets. However, it can take 30 to 60 minutes of darkness for the rods – the most sensitive part of the eye – to acclimate, and for “dark adaptation” to take place (see graphic below). In fact, it is believed that only after several whole days of darkness do our eyes reach absolute maximum light sensitivity. The amount of night sky objects you can see as your eyes adjust increases dramatically.