I observed the total lunar eclipse on 28 August from my farm in southern Indiana. Conditions were very good for a late August evening in the Ohio valley. I decided to try my hand at imaging the eclipse with both a tripod mounted digital camera and a Meade LPI USB camera mounted on an ETX90EC. I intended to attempt the eclipse timing experiment proposed by John Westfall but unfortunately misunderstood when to expect “first contact” of the umbral shadow.

I began setting up the camera and telescope at about 0845 UT (4:45 EDT). By approximately 0852 UT the umbral shadow was clearly visible and I began to realize that I’d goofed on my estimation of first contact. I began observing in earnest at 0900 UT (5:00 am EDT). The plan was to fix the tripod mounted camera and take a series of images spaced at 3 minute intervals.

Naked eye timing of “second contact” (umbral shadow across the full lunar disc) was 09:51:32 UT. I continued to observe totality until approximately 10:15 UT when the Moon’s disc dropped into the tree line on the southwestern corner of my property. I found this eclipse to be somewhat darker than recent lunar eclipses at approximately 2.5 on the Danjon scale.

The eclipse composite was taken by Duke Marsh in New Albany, IN. The lower image was taken using the LPI/ETX at approximately 0931 UT. Click on the images to enlarge them.  I invite you to submit your eclipse images and will post them here on StarGeezerAstronomy.com Message me here about sending your images.

If you participated in the naked eye eclipse timing experiment please report your observations to John Westfall

Our interview with Dr. Westfall regarding the naked eye timing experiment is interesting listening, even after the eclipse. Click the “play” icon below to listen

A bogus or seriously misguided email is circulating on the Internet.  It claims that Mars will be historically close to Earth on August 27, 2007–so close that Mars will look as large as the full Moon.

This is the fourth time around for the “story”. In 2005, prior to the last opposition of Mars I received dozens of emails, telephone calls and requests for interviews from the media.The story is not true, but it got me wondering how close would Mars have to be in order to appear the same size as the Moon.

I asked Scott Miller at the University of Louisville’s Rauch Planetarium. Scott provided the following formula. Can you solve this problem? Scott wrote:

Simple enough - use the small angle formula:

D = ad/(206265)

where D is the linear size of the object (the diameter of Mars in this case), a is the angular size of the object (half of a degree or 1800 seconds of arc - the necessary unit of measure of the angular size in this form of the equation), and d is the distance.  So, solve the equation for d and you will get that distance in the equivalent unit that you use for the numerical value of the diameter of Mars.

I also contacted Dr. John Kielkopf with the University of Louisville Physics Department  and asked about the tidal effects if Mars were close enough to subtend the same angular size as the Moon. According to Dr. Kielkopf:
 

At  the 2005 opposition the maximum apparent diameter of Mars was 20.1 seconds of arc.  For comparison, when the Moon is at perigee as seen from the center of the Earth it is 33.53 minutes of arc or 2012 seconds of arc in apparent diameter.  Actually the Moon is even bigger because we see it from the surface of the Earth rather than from the center, but let’s ignore that. Now suppose that Mars were close enough to make it appear as large as the Moon in the sky.  That means it would have to be 100x closer than it was at the 2005 opposition.  Tidal effects go as the cube of the distance, and in this bizarre case tides raised by Mars would be 1,000,000 greater than “normal”. How large are the tides from Mars?  Compared to the Moon at perigee the tides from Mars at the 2005 opposition were 1.2 millionths of the tides due to the Moon.  You can check this for yourself.  Tides are proportional to the mass of the object raising the tides, and inversely proportional to the cube of its distance. The bottom line is that if Mars were close enough to appear to be the size of the Moon, then  the tides it would raise would be nearly the same as those due to the Moon when it is at its closest to Earth.  It turns out that the reason they are nearly the same is that the Moon and Mars have roughly the same density.–John Kielkopf

As August, 2007 begins Mars is “getting good” again. It is now rising around midnight local time and will be at opposition in December of the year.  The “Mars Hoax” email first surfaced in 2003.  On August 27th of that year, Mars really did come historically close to Earth. But the claim that Mars would rival the Moon was grossly exaggerated. Every August since 2003, the email has staged a revival.  It’s as wrong now as it was then.Make the formula calculations and let me know what you come up with. In 2003 the Red Planet came within about 35 million miles of Earth. Last year’s opposition brought it to within about 41 million miles. How close do you think Mars would have to be to appear the same size as our Moon? Send me an email with your answer.