Watch Mercury cross the sun Nov. 8
By RYC RIENKS
This is an amazing week! As I mentioned last column we have a fairly rare event transpiring Nov. 8. Mercury will transit, or pass across, the face of the sun. Observers in Baker City are perfectly positioned to witness the entire passage. Mercury begins its pass at 11:12 a.m. and finishes its journey at 4:10 p.m.
Thanks to Thatcher's Ace Hardware, I will set up in their parking lot to observe and record this event. I will time the ingress and egress and take a few photos during transit. Please drop by to discuss and observe this event with me.
The following equipment will be available: A Meade ETX-90 telescope with solar-filter, a demonstration Specto-Helioscope, and binoculars for image projection.
The spectro-helioscope will show the sun's spectrum in small scale. Spectrum analysis is one important method of gaining information about all light emitting or reflecting bodies. This particular instrument is too small to see spectral lines but the spectrum shows well.
You can try casting an image by projection at home. The difficult part is lining up on the sun. One safe method is to rest binoculars (with one of the front lenses covered) or a spotting scope on your shoulder as you put your back to the sun. Minimizing the shadow of the binoculars/scope will bring them into alignment. An image of the sun will shine in the middle of the shadow cast by the binoculars. This takes some practice and patience. Project the image onto a clean sheet of white paper or cardboard. Move backwards or forwards until you have an image about eight to 10 inches in diameter. Move slowly to the right to maintain the image as the earth rotates you away from the sun. The rotational rate is one degree in four minutes. The altitude of the sun is 28 degrees from 11 a.m. to noon. Thereafter it begins to drop a little. One note of caution: the partially focused heat of the sun can melt internal plastic parts fairly quickly. I have used this method with quality scopes and binocs with no ill effects. Trying this with a cheap telescope, however, melted the aperture stops. If in doubt, stop by Ace with your item and ask me.
For direct viewing use a welder's mask or goggles with a #12, #13 or #14 glass. These are safe for short exposure. Do not use any lower number glass or other improvised devices for looking at the sun as there is danger from both the visible and the non-visible parts of the spectrum. Protect your eyes. If in doubt, don't try to look at the sun. Stop by Ace for a peek through equipment that is proven safe for solar observing.
While watching Mercury in its travels you will also see a rather spectacular sun spot near the western limb, NOAA Active Region 10921. This is a complex of darker areas on the sun's surface caused by twisted lines of magnetic force interfering with the convection of heated particles traveling from the depths of the sun. The sun spots are several thousands of degrees cooler than the surrounding area and thus they appear as dark. AR 921 has been working its way towards the western edge of the disc and will rotate from view if it doesn't fade away. It is a large and fairly complex spot but seems to be dissipating in the most recent views.
CORRECTION: I stated this wouldn't happen again for 122 years. That was an error caused by thinking of two different events and combining the data. The next transit by Mercury is May 09, 2016 at 14:57 UT or about nine and a half years. Venus transits in 2012 then not again for 122 years. Sorry for the sloppy proofreading.
METEORS: Meteors this week are the Northern Taurids, which are similar to the southern Taurids. Look for more meteors. A chance for fireballs exists. Peak activity comes the 12th.
Birthdays This Week:
Nov. 8 is Edmund Halley's 350th birthday. Born in 1656, he identified the orbit of the comet which bears his name. Halley's Comet returns every 76 years.
Nov. 11 marks the birthday of Vesto Slipher, born in 1875. He was the first astronomer to photograph galaxy spectra and measure their red shifts. This led to Edwin Hubble's discovery of the expansion of the universe. See the image in my spectro-heliograph for an idea of his achievement.