January 20, 2000 - Lunar Eclipse

David Lee & Richard Harvey

On January 20th, weather willing, we will be able to view a total eclipse of the moon from beginning to end. The last time this happened was September 26th 1996. At this time on the west coast we were only able to see the last half of the eclipse. At dusk the Moon was already totally eclipsed. On the 20th the full sequence events will be available to us starting at 6:30pm PST for the very earliest indications of the eclipse. Don't miss this one, there won't be another until May 19th 2003. More details can be found in this article and at the Sky and Telescope and Astronomy websites. - David Lee

NASA link for total lunar eclipse: http://spacescience.com/headlines/y2000/ast19jan_1.htm

What's Happening

A total lunar eclipse occurs when the Earth comes between the Sun and the Moon. During a lunar eclipse the Moon's position traverses the Earth's shadow. The Moon's first contact with the Earth's shadow is at the outer band of the shadow called the penumbra. The light falling on the Moon is progressively blocked until at the moment of total eclipse the Moon is completely in the darkest central area of the Earth's shadow called the umbra. At the point of total eclipse the process starts to reverse itself until the Moon is totally out of the Earth's shadow.

Observing Tips

What do you need ?

Everything from your eyes, binoculars and telescope are suitable. Bear in mind this is a long process and at this time of year dress warmly if you want to be comfortable.

Find yourself a location that has a clear horizon view of the east especially if you wish to view during the early stages.

Keep a log of what you see and note the time. Pay attention to how much of the light on the moon is obscured and if there are any colouration changes. During the total eclipse the Moon will take on a deep orange-red colour. Historically the eclipses from the last decade have been tainted with the debris from volcanic eruptions that occurred in the early 90's resulting in a deeper coloured and darker total eclipse. Studies have indicated that the atmosphere has cleared most of these contaminants and should have an effect on the look of this eclipse. There are no guarantees however as the atmosphere is highly volatile. We'll have to wait and see for ourselves.

Photographic Tips

Equipment

Any camera with the capability of setting shutter speeds and aperture settings manually will do fine. The ability to use interchangeable lenses will be an advantage for more detailed images of the Moon. For the darker parts of the eclipse eg. totality you should use a tripod support for best results. If you have access to a telescope you can try capturing the event using prime focus techniques through the telescope optics.

Film

Film is very much a personal choice. Today's emulsions are very fine-grained and detailed in spite of their rated speeds. Don't be shy to use ISO 400 or even ISO 800 film. Given the speed of the optics you are using you may have to opt for a higher speed film anyway. For astronomical subjects using negative film I've always been a great fan of Fuji Super G 800, you'll need to go to a camera specialty store for this one. Another good film is the more current and easily obtained film Fuji Superia 400. For slide film I understand the Kodak Ektachrome Professional E200 is an excellent film with good pushing capabilities although at the expense of increased grain.

Technique

The simplest eclipse pictures can be taken with a manual camera and a normal lens, preferably supported by a tripod. For best results use a cable release to minimize vibration. Images taken in this fashion result in a small lunar image. This is why it is preferable to use a telephoto lens to photograph the Moon. For a 35mm camera try a 200mm lens or something close to this, even better a 500mm lens or higher. You may also use teleconvertors to increase magnification, these typically come in 1.4x and 2x strengths. Their downside is they reduce the effective aperture of your optical system. A 1.4x teleconvertor will decrease your effective exposure by 1 stop, a 2x teleconvertor will decrease your effective exposure by 2 stops. Work out your effective aperture of your optical system ahead of time so you don't have to think about it on the night of the eclipse.

Example:

To achieve any higher magnfication than what is stated above you will have to use a telescope at prime focus. For this your manual camera does need to have the capability of using interchangeable lenses. For prime focus you will use the telescope optics as your interchangeable lens. To attach your camera to your telescope you will need two things a T-adapter that fits your camera and a telescope camera adapter that fits your telescope. The telescope camera adapter is designed to fit in the focusing tube of your telescope and is threaded to accept the T-adapter of your camera. With the magnification involved with telescopic optics it is likely that you will need to use a tracking mount. Preferably the mount should be able to track at lunar speed as opposed to sidereal but if the shutter speeds chosen are shorter than 1 or 2 minutes this is not critical.

Exposure times are the next consideration. The following exposure times are based on a medium speed film and an effective aperture that would be common with a long telephoto and teleconvertor combination. Exposures may vary with your equipment based on ISO speed of film used and effective aperture. The Danjon Lunar Eclipse Luminosity Scale has been included to provide better guesstimates for totality.

After giving some exposure recommendations remember the cardinal rule about photography ... bracket. Always try exposures plus and minus your chosen exposure. This gives you a better chance at getting usable results. Let's all hope for clear weather and good luck. If you have any questions please send email to David_Lee@telus.net .

Star Hop for Eclipse Night

So photography is not your thing and it's a long wait for the changes ... here's a star hop for eclipse night from Richard Harvey - David Lee

Some treasures in the sky around the Moon - Richard Harvey

As the Moon gradually enters the Earth's shadow, fainter and fainter stars will one by one spring into view around its perimeter. Shortly after 8 pm the Moon's light will have faded from a dazzling magnitude of -12.5 to +3 -- representing a decrease factor in luminosity of more than 1.5 million in about an hour -- and the winter constellations will then be shining in their full glory. That resplendent region of the sky, from the Bull to the Twins, the Big Dog to the Charioteer, and Orion the Hunter as the reigning King, will be hosting the Moon on her voyage across the sky, on this fine January evening.

We are looking away from the center of the Milky Way Galaxy across our own arm (called the Orion Arm), in effect gazing across its full thickness from a vantage point near its inner edge.

As such we have access to a spectacle of luminous and massive young stars whose bluish light help define the spiral patterns in galaxies such as our own. This is the main reason why the winter sky contains many of the brightest stars in the sky, and seven of those define what is known as the Winter Hexagon -- a large asterism comprised of seven of the brightest stars in the sky, confined in a region of roughly 40 by 60 degrees and completely encircling the winter Milky Way.

During the 77 minutes that the Moon deprives herself of the Sun's rays,why not take advantage of the sudden dark sky (if you're out in the country of course!) and admire the asterism with your naked eye and hunt down some of the fainter targets with binoculars?

As the Moon enters totality at 8:07 pm it will lie on the northeastern edge of that pattern, as one gazes almost due East and about 20 degrees above the horizon. Before starting on our tour however one cannot miss a remarkable cluster of stars called the Beehive Cluster, 44th entry in Messier's list, a mere 6 degrees or so east of the crimson Moon. The two will easily be visible in the same 6-degree binocular field and should therefore be a memorable sight!

After admiring the view for a few minutes, aim your binoculars straight up by two fields of view (or about a fist's width held at arm's length), and there comes Pollux who shines with an orange hue at magnitude 1.1. At 34 light years, Pollux is one of the nearer stars to our Sun, as is Castor, his celestial neighbour, at 52 light years. Together they define the northeastern apex of the hexagon. An interesting fact about Castor is his sextuplet nature: no less than six stars form a complex multiple system, with three visual components visible in many backyard telescopes, each of which forming a spectroscopic binary. By placing Pollux at the upper left side of your binocular field of view, you should be able to pick up a relatively faint open cluster: NGC 2420, along the lower right edge. Try to see if you can detect this rich cluster of 30 odd stars fainter than 10th magnitude, which should be seen as a hazy patch of light. Also, for those with instruments larger than 6 to 8 inches, try to hunt down the Clown Face (or Eskimo) Nebula, a magnitude 8 planetary nebula about 2 degrees east of 2420.

Continuing about 30 degrees (three fists) to the northwest, brilliant Capella shines at magnitude 0.08, placing it 6th in the list of brightest stars. It is a class G giant at a distance of 42 light years -- again relatively close to our Sun-- and is a spectroscopic binary. Here we are at the top vertex of the Winter Hexagon, in the constellation Auriga. That area between Auriga and Gemini contains a wealth of open clusters starting with M35 about 3 1/2 binocular fields west of Pollux, at the right foot of Gemini,or 2.5 degrees northwest of eta Geminorum. With binoculars the cluster should appear as an easily detectable patch of light with perceptible granularity. Proceeding from there about 2 fields straight up (that is, northwest) from M35, and a memorable trio of clusters in Auriga await your visit: M37, M36 and M38, with the most prominent being M37, being particularly rich with some 150 stars compressed in a diameter of 20'. Even more remarkable: all three can fit in a binocular field. The area is carpeted by other lesser known and fainter clusters: try to see of you can detect the slightly fainter open cluster NGC 1893 about 2 degrees (or 1/3 of a field) to the right of M38.

At the foot of Auriga lie the horns of Taurus, the Bull, as he stares at us with its only eye, Aldebaran, about 30 degrees southwest of Capella. Look for a V-shaped cluster of stars just to the right, called the Hyades, one of the closest open star clusters at 150 light years. Although the Hyades can comfortably fit in a binocular's field, a more pleasing view remains that with the naked eye. At magnitude 0.9, Aldebaran is a K-class giant and only lies at 65 light years from our solar system, thus discarding its membership in the Hyades. Ten degrees northwest of the Hyades lies an even more famous cluster: the Pleiades, or Seven Sisters, revered by all civilizations since Antiquity. According the Burnham's Celestial Handbook, one possible origin of the name comes from the Greek "pleid", meaning "to sail", referencing to the first rising of the Pleiades to announce the Mediterranean navigation season. A spectacular sight even with the naked eye, this 400 light year distant cluster contains relatively young, hot blue stars. The brightest member of the cluster is called Alcyone and outpours about 1000 times more energy than our Sun, and is probably about 10 times greater in size! All members fit within a binocular's field and produce a beautifully compact dipper-like shape, with dozens of fainter members visible.

Continuing on our quest, we meet a giant among Giants, Rigel, at the southwestern tip of our hexagon, lies about 25 degrees southeast of Aldebaran, and represents the right foot of Orion the Mighty Hunter. Orion is the showpiece of the constellations and contains a superlative set of objects ranging from supergiant stars to bright star forming regions. Rigel is one such supergiant and although it lies at a colossal 770 light years, it still manages to shine at magnitude 0.2, ranking as the 7th brightest star in our sky! Here are some numbers to impress you: Rigel is 50000 times more luminous than our Sun, is about 30 times larger and is one of the most luminous stars in the Galaxy! Although not part of the Hexagon, another supergiant called Betelgeuse lies at the opposite end of Orion and shines with an unmistakably red colour. This star is so huge that if placed at the center of our solar system, its distented surface would reach beyond the orbit of Mars! Betelgeuse is the largest star within 1000 light years of the solar system. Of course, one cannot miss the mystic three-star alignment of Orion's Belt: Alnitak, Alnilam and Mintaka, and if you maintain the stars in the upper part of your binocular field, you eyes will be drawm at the bottom toward the Great Nebula of Orion, or less romantically called M42. At 1500 light years distant this is the most famous galactic region where new stars are being born out of a huge mass of molecular hydrogen, which surrounds the entire constallation. The glow of M42 is due to hydrogen atoms being violently ionized by the ultraviolet radiation outpouring from the hot young stars in its center. Any instrument larger than 3-4 inches will reveal spectacular structure.

Proceeding across the sky another 25 or so degrees to the eastsoutheast we come across Sirius, the Queen of stars from our vantage point, at magnitude -1.4, even though its luminosity is only that of a main sequence A class star. Its great brightness is mainly due to its proximity: at 9 light years, she's practically in our backyard! This region is again plastered with numerous galactic open clusters such as M44, the Messier object almost 4 degrees due south of Sirius, and lying well within the same binocular field, a pair of clusters: M46 and M47, about two fields east of Sirius and finally M50, 1 1/2 field of view north of Sirius.

By the time you reach this rich area, the Moon will have probably travelled along its orbit just enough to touch to eastern limb of the Earth's shadow, effectively ending the phase of totality: it is just after 9 pm. We therefore finish off our grand tour with Procyon, the star that defines the Eastern edge of the Winter Hexagon. At 11 light years distant, and a magnitude of 0.4, this is an F class main sequence star.