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About the Stargazer

Arnold Medalen, USPS Stargazer

Arnold Medalen

USPS member Arnold Medalen belongs to California’s Diablo Sail & Power Squadron and has been boating in the California Delta and San Francisco Bay since childhood.

The Stargazer first came to appreciate the night sky while boating in the Delta, far away from city lights. Today, he boats with his wife, Patricia, aboard Shelly C and volunteers on the United States Power Squadrons Communications Committee.


1. Steve Steadman - 31 January 2010

Hey Arn, correct me if i’m wrong, isn’t Orion & Plasaidies(?)(Seven Sisters) in the Southern Hemisphere?

Arnold Medalen - 2 February 2010

Thanks for your question

The Pleiades star cluster has a declination of about 24 degrees north, placing it well into the Northern Celestial Hemisphere.

Orion straddles the celestial equator. The northernmost main star of the body is magnitude 0.6 Betelgeuse with a declination of about 7 1/2 degrees north. The southernmost star of the body is magnitude 2.2 Saiph with a declination of nearly 10 degrees south. The belt lies nearly on the celestial equator.

Steve Steadman - 9 February 2010

Sounds Greek to me. LOL I could have sworn it was the Seven Sisters i saw, i first saw that cluster when i was a kid in Pittsburgh.

I see Orion just about every night when i walk my dog but the city lights wipe out the stars. I like going to the Desert at night and looking at the Stars and Meteors, man there’s billions of them.

I’m not a big Stargazer but i do enjoy looking at them, it’s like looking into the past because some of them aren’t there anymore.

2. Ken Molloy - 10 January 2011

What longitude are you at? It seems that a lot of your viewing comments (sunrise/sunset star amd moon positions) are truly valid only at one longitude.

theensign - 21 February 2011

Thank you for your question. It is always good to hear from readers.

You are absolutely correct that the local time of rising and setting of all celestial bodies is affected by longitude. As you move west within a time zone, events happen later. For example, if you were at the eastern boundary in ZD +7, 97.5 degrees west, sunset on 1 March 2011 is at 1723. In the middle of the zone, 105 degrees west, sunset is at 1753. Near the western boundary, 112.5 degrees west, sunset is at 1823. Stepping a few feet west into ZD +8, adjusting your watch back 1 hour, sunset would once again be at 1753. Times are also affected slightly by latitude.

For this reason, I rarely, if ever, use local time when referring to celestial events. I will either use UT (GMT), or reference an event a certain amount of time before or after sunrise or sunset. For example, on 20 February, Saturn and the moon rise side-by-side 3½ hours after sunset. Please keep in mind that I use approximate times solely to give the reader a general idea where and when to look. Actually the moon rises 3 hours 23 minutes after sunset and Saturn rises 3 hours 28 minutes after sunset. From a practical amateur stargazing point of view, the timing of an event in relation to sunrise, sunset, moonrise or moonset is not significantly affected by longitude.

As far as the positions of stars and planets in relation to the moon are concerned, these are also not significantly affected by longitude. They are very significantly affected, however, by the time of viewing. First, from our viewing perspective here on Earth, the moon traverses the night sky slightly slower than the background stars. It moves slightly eastward in relation to the background stars as the evening passes. For example, in the early evening of 20 February, Spica is about 9½ degrees east (lower left) of the moon. Before dawn on the 21st, they are separated by less than 7 degrees. In addition, their relative positions have changed. Spica is now to the upper left of the moon. For these reasons, when giving position and distance of a body in relation to the moon, I try to give a general viewing time such as “early evening” or “late evening.”

–For Arnold Medalen, USPS Stargazer

3. Mike Collins - 18 February 2014


I notice in the Ensign magazine for Q1 2014 that the entries for25 JAN, 20 FEB and 18 MAR are in red ink and the rest of the entries are in black. Is there any significance to that?

Mike Collins

theensign - 16 June 2014

Sorry for the delayed response. The editors always highlight one day for the calendar, a not-to-miss item if you will.

4. Ken Peters - 22 August 2014

Thanks you for alerting us to the narrow separation between Venus and Jupiter on the 18th of August. It provided interesting morning observations over the past weekend through Tuesday morning.
Using hourly GHA and Dec date from the NA I calculated the smallest angle to be 0.198 degrees at 0500Z on the 18th. I used the USPS Cos and my Haversine methods with an absolute difference of 3.3E-12 degrees between the two.
My question is the 0.01 degree difference between your 0.21 and my 0.20 calculations. What have I done wrong?
If you are interested in pursuing this further I can send you my Excel workbook.
Thank you for providing your Stargazer piece each week.

amedalen - 24 October 2014

I’m sorry it has taken so long for me to respond. I don’t think you have done anything wrong. Without going through the math in detail, my best guess is the 0.01 degree is a rounding difference. And, for our purposes, 0.01 degree is not particularly significant

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