Discovery, promotion and demotion of Pluto

bryan shumaker web art

Sixteen inches and what do you know, another week older and deeper in snow! I suppose the skies will eventually clear, but I’m at the point where I may have forgotten how to use my telescope. We can only hope we get a chance to do some night sky observing before spring arrives!

On February 4, 1906 Clyde Tombaugh was born. Pluto was discovered February 18th, 1930 by him at the Lowell Observatory in Flagstaff, Ariz. Astronomers were certain that there were more planets in the outer Solar System.

The director of the Lowell Observatory handed the job of finding this next planet, dubbed “Planet X” to the 23-year old Tombaugh. Tombaugh used a tool called a “blink comparator” to compare two photographs of the night sky. He worked methodically, comparing two photographic plates, looking for any object that jumped from one night to another night. And finally on February 18th, 1930, Tombaugh discovered Pluto; a faint object in the right orbit.

The name for Pluto was chosen by an 11-year old British school girl named Venetia Burney.

This continued the tradition of naming planets after Roman gods. Pluto was the Roman god of the underworld, the same as Hades in Greek mythology.

It also matched the first initials of Percival Lowell, who the observatory was named after. Lowell died in 1916, and so he never saw the discovery of Pluto. As you all know by now, Pluto was “demoted” from being a full planet to a “dwarf planet” several years ago.

This week brings us to the first quarter moon on February 6, so if the skies do clear, this whole week is a great time to do some lunar observing.

The best views of the moon are not when the moon is full, but when only partially illuminated. The best place to look is the line where the sunlight and the darker, unlit portion meet. Called the terminator, it provides excellent contrast to the surrounding moonscape.

There are a number of free and minimal cost lunar atlases available on-line and at your favorite app store, so if this does interest you, it might be fun to have an atlas available to help identify the lunar surface structures.

So, is there any way to have a realistic sense of whether or not the skies might clear in the next 48 hours?

Astronomers use many sources, but the best local source which is amazingly accurate is generated by the Canadian Meteorological Survey and updated daily.

It shows the weather prediction, hour by hour for the next 48 hours. Accurate? If it says the weather will be good for observing only between 1 a.m. and 2 a.m., believe it!

Mr. Danko, who wrote the software and does the updates, has a great web page that explains how it works.

Several parameters are evaluated and carefully explained in each prediction.

Raven Hill Discovery Center in East Jordan is one of the designated sites.

Check out for an overview, and is the specific URL address for Raven Hill. Easier still is to go to the NOMAC web site and click on the right side of the page on the dark sky prediction graph.

The measurements are for cloud cover, transparency, seeing, and darkness. Each of these parameters is explained simply and clearly, so you have a very good idea what is expected. Make sure you check it out!

I just want to remind you that the next meeting of NOMAC (Northern Michigan Astronomy Club) at Raven Hill is at 7:30pm on February 6. Hope to see you there!