October 2010

Tony Martinez

Each month I will describe sights of interest in the night skies of South Carolina. These sights will be broken down into three sections; what you can see with the naked eye, with binoculars, and with a small telescope. The best time to view the night sky is at and around the times when the Moon is not visible, what is known as a New Moon; which will occur this month on October 7th. For October, your best viewing nights will be from October 1st through October 13th. The Star chart below is set for Florence, SC on October 15th at 9 pm.

Clear Sky Clock:

This month as you stand under a clear starry night, you may notice that Jupiter’s bands and Messier Objects are not very clear. Your problem is that you assumed that a “clear night” reported by your local weather site also meant a clear night for amateur astronomy; this is not always true.

What an amateur astronomer needs is a weather site designed specifically for astronomers. The site of choice is called “The Clear Sky Clock.” This site gives viewing forecasts for 4048 locations, covering the entire United States (except Hawaii), all of Canada, parts of Mexico, and the Bahamas. The location closest to Florence is the Francis Marion University Clear Sky Clock; http://www.cleardarksky.com/c/FMUObSCkey.html?1. When you go the site to check out the viewing forecast, you may be perplexed. You won’t see any maps or radar, etc; instead you see only a bunch of small colored squares. Therefore, I would like to take time this month to describe how to use this astronomer’s weather site.

First of all, the times listed on the site use a 24-hour clock, the vertical red line denoting midnight. Next, notice that in the far left, the vertical bands tell you that the top four lines of little squares refer to sky conditions, and the bottom three lines of squares refer to ground conditions. These bottom three lines, wind, humidity and temperature, are there primarily there to tell you what clothing, etc. that you might need that evening. Therefore, the top four lines of squares (sky conditions) are where you focus your attention.

For all sky conditions, dark blue squares are great, and white squares are bad. Next, notice that the fourth row of squares, from the top, is for darkness. This information has the least use since you know when it is dark outside. The first row denotes cloud cover. Dark blue, no clouds; white, total cloud cover; and pale blue, partly cloudy. The next two rows supply you with the information that no other weather site will give you. The “transparency” row refers to the amount of moisture in the atmosphere. Excessive moisture in the atmosphere will definitely affect your viewing. The “seeing” row refers to atmospheric turbulence due to temperature differences. Therefore, you can have a cloudless night with low atmospheric moisture, and still not be able to resolve the cloud bands on Jupiter because of poor seeing. So, go to the Francis Marion Clear Sky Clock, check the time of night that has all dark blue squares in the first three rows, and go outside and enjoy the stars.

Besides “Clear Sky Clock” basics, there is other interesting information available. If you are a visual type person, you can click on any small square and it will show you the visual map that refers to that information. Also note that you can animate the map if desired. The image below came from clicking on the cloud cover square at 1300 hours on September 28th; note that the crosshairs denotes the Clock’s location.

Next, look to the right side of the main page of the Clear Sky Clock at a green box labeled “Other Charts.” In this box you can go to all the Clear Sky Clocks in South Carolina, or those nearby Francis Marion University. In addition, you can click on “All,” which will direct you to all 4048 locations. Now notice that you have a choice of “List” or “Map.” If you click on South Carolina List, you will go to the image shown below.

This is an interesting page. It gives a list of all the Clear Sky Clocks in South Carolina, along with comments and links for most sites. Next, under the heading, “Preview,” is a column of the actual first two rows of every site. A quick view of the image shows that the best observing site in South Carolina for this time period is at the “Dixson Lomax Memorial.”

Before leaving this page, note that there is a vertical column of colored squares in the center of this page, under a heading of light pollution. Click on the heading, and you will see an explanation of the colored squares. Note that black means no light pollution at all, and white means too much light (cities, etc.) for amateur astronomy or naked eye viewing. You will also notice that no site in South Carolina is better than a green square, with Florence having only a yellow square.

Now return to the Green Box on the main page, and click on South Carolina “Map.” Now you have a map of South Carolina with all the Clear Sky Clock locations represented as a “push pin” matching the color of the light pollution for every site in our state.

I find it fun to check state lists and maps to find where in the United States might be a good place for an astronomy vacation; check out the southwestern states.

It might be a good week to visit the Hideaway Observatory near Duncan, Arizona.

Naked Eye Sights: Venus is now leaving us, and Jupiter will continue to be the brightest “star like object” this month.

Binocular Sights (7 to 10 power): View the double cluster in Perseus on October 9th, and you may see a comet; 103P/Hartley.

Telescope Sights (60-100mm): Jupiter remains the best target for this month

Comments are closed.