Moony Monday!

.....I said "Moony Monday" for the Total Lunar Eclipse that will occur early Tuesday morning because I couldn't think of anything that went with Tuesday. The universe is not rewarding this, however, since there is a winter storm warning with 5-8 inches of snow on the way, finishing up with frozen rain. I hope someone else out there gets a chance to see this.

.....To see this, all you need is a good view of the skies (from the Americas, and best set up for North America). If you have a telescope, or even binoculars, that will make things even better, but it isn't necessary.

The first stage is when the Moon enters the Earth's penumbra, the shadow where part of the Sun, but not all of it, is blocked. This will be pretty much undetectable. The Moon enters the penumbra at: 11:46 PM (CST/ UT -6, which is 12:46 AM Tuesday in the Eastern Time Zone, and 10:46 PM in Mountain Standard Time, and so on.)

.....The Moon enters the umbra, the central shadow at 12:51 AM (again, CST, the best time zone) , and totality, with the Moon entirely in the umbra from 1:57 AM to 3:14 AM. On Earth, a total eclipse is completely dark, but in a lunar eclipse the light passing through the Earth's atmosphere is scattered into the shadow. In the same way that the sky appears blue because blue light is scattered first, and the setting Sun appears red because red light is scattered last, the totally eclipsed Moon will appear a deep red, sometimes getting so faint that the full &^$%&^% Moon is hard to find in the sky.

.....The Moon leaves the umbra at 4:17 CST, so the party is then pretty much over.

.....Since this lunar eclipse happens on the Winter Solstice (when the Sun is at its lowest point in the sky), the Full Moon (exactly on the opposite side of the sky) will be at its absolute maximum possible highest. I'm honestly fairly amazed that no group has come forward claiming some mystic significance for the occasion. There is definite non-mystic significance, because this is the last total lunar eclipse visible from North America until April of 2014.

.....If you do get a chance to see it, please let me know; I'll be watching the snow fall, grading final exams.

An apology

.....Wow, looking at the time that has gone by, while I very much want to provide a blog that is aimed at those who might not be in the middle of the country with years of experience, I've first gotta go with my teaching responsibilities. Still, I am working toward building up a "Year around the Sky" to start in May. I will still be updating this as often as I can.

Aquila: The Eagle Has Landed

..... The southern star in the summer triangle is Altair, which means "the Eagle". (Vega, in Lyra, also means "the [Diving] Eagle.") Altair is the brightest star in the constellation Aquila (the Eagle) which is shown in the map below along with the constellations Sagitta and Scutum, which a reasonable reader at this point might conjecture mean "the Eagle" and "the Eagle", respectively, but surprisingly this turns out not to be the case.

.....Altair is the closest of the stars in the Summer Triangle, being about 16.77 light years away. The light that reaches the Earth on the night of September 20th, 2010, left the surface of Altair on December 13, 1993.

.....The constellation Aquila is a fairly large constellation in the center of the summer(/autumn) Milky Way. The view of the Milky Way in the sky even shows a split, with the Milky Way having apparently separated into two bands. This appearance is actually due to tremendous clouds of neutral hydrogen gas and dust between us and the center of our galaxy. We're looking in the direction of a tremendous number of stars, which makes it surprising that Aquila has no deep sky objects of interest in the reach of a small telescope.

.....This lack of cool stuff is why I added the constellations of Scutum and Sagitta to this map; I'm going to describe the telescopic objects in these two constellations in Aquila's place, since Aquila is easy to find, but doesn't have anything of its own.

.....This constellation also stands out to me because I now live in an area in which eagles are reasonably common sights. Just last weekend on our drive along the Mississippi to town, we saw two eagles flying over the road. Upriver in Wabasha is the National Eagle Center, located here because it is the northernmost point along the Mississippi the does not freeze over, so there are many bald eagles that winter in this area. In January and February it is possible to see dozens of eagles along the river, and I don't think that there has been any times in which I have gone there that I have not seen any eagles in wild.

Deep Sky Objects in Lyra (L2/M57, M56)

.....There are two Messier objects in Lyra, and the up side to Lyra's small size is that I can fit the entire constellation figure on the finder chart for both objects. Lyra contains one of the most impressive, and easiest to find, Messier objects.

Messier 57 / Leckenby 2: The Ring Nebula

.....The Ring Nebula, aka M 57, aka NGC 6720, aka L2 (my designated second object on the "Leckenby list", my list of deep sky objects that a starting observer has a really good chance to locate) is located between the bottom two stars of Lyra, Sulaphat and Sheliak. In a good pair of binoculars, the Ring Nebula can be seen a little bit closer to Sheliak than Sulaphat.
...In a telescope, the Ring appears as a, well, ring. The Ring Nebula is a "planetary nebula" (due to its round appearance), and in the simplest model of a planetary nebula, it represents what will someday happen to the Sun. When nuclear fusion finally stops at the core of the Sun, the core will collapse without that energy being added to it, and that collapse will release energy that will bounce off the outer part of the Sun like an expanding soap bubble. As it turns out, things are a little bit more complex; the Ring isn't actually a spherical bubble of gas, but more of a cylinder that we are looking at edge-on.

.....Below are two images, one of which might be a mistake to include. The one on the left is a sketch I made of the Ring Nebula through my personal telescope. This is probably fairly close to how this object might look to the typical backyard observer. The other image is a Hubble image of the Ring. This object will *never* look like this in your backyard, I'm sorry.

Messier 56

.....Messier 56 isn't viewed as often as, say, the Ring Nebula, because M56 is a globular cluster, and there are dozens of globular clusters visible during the summer. Given a choice between M56, and something like the Hercules Cluster or M5 in Serpens, most people will go for one of the biggies. The most dramatic globular clusters appear as a bright central blur that resolves itself into individual stars as you get farther to the edge. That resolution does not appear with M56, at least it didn't with me. (The seeing the last night I looked at it was not the clearest, however.)

.....the Messier Objects were originally compiled into a list by Charles Messier because he was looking for comets, and these were things that kinda looked like comets, but weren't. Author Stephen James O'Meara has noted that M56 is special to him because it has a hazy, comet-like appearance, so it shows what Messier found distracting when he made a list of what we now recognize as a tour of the wonders of the sky when Messier was just trying to list the garbage that kept getting in his way.

Lyre, Lyre

.....Lyra the lyre is the first of the constellations of the Summer Triangle; a small constellation consisting of a triangle of stars joined to a parallelogram, but easy to find because it contains one of the brightest stars in the sky. The westernmost star in the Summer Triangle is Vega, and when you can see it over the horizon it the fifth brightest star in the sky. (If someone is reading this over your shoulder, they probably made some joke like, "except for the Sun, dude." I'll wait for a second if you choose to slap them.)

(All good? Yeah, I feel better, too.)

.....Vega is actually one of the stars we use to define the "magnitude" scale that defines the brightness of stars. Originally, this system goes back to the Greek astronomer Hipparchus, who defined the brightest stars as "stars of the first rank" and the dimmest stars as "stars of the sixth rank". Now that we can use cameras to measure exactly how much light we receive from a star, it is now possible to be a little bit more precise. Vega and Arcturus (in Boötes) were use to define zero magnitude. In this reconstructed system, stars with a magnitude of 1.00 are bright, stars with a magnitude of 6.00 are just barely visible one a clear, dry, dark night, and the Sun has a visual magnitude of -27.
.....The only stars brighter than Vega are Arcturus (just barely), Sirius (a winter star), and Canopus and Rigil Kentaurus (stars not visible from the middle and upper United States).

.....The second brightest star in Lyra, Sheliak, is special in another way. Like most stars, it does not travel through space on its own, but Sheliak is actually two stars orbiting closely to each other. As I said, most stars travel in pairs (or more), but these two stars are orbiting so closely to each other that the shape of both stars is distorted, and material is apparently escaping out of the "back end" of Sheliak A. Incredibly funky physics, but you can't see anything through a telescope.

.....What you *can* see in a telescope is Epsilon Lyrae, the other star in the triangle at the top of Lyra. This might look a little funny in the star map, and this star in even a good pair of binoculars will be revealed as a pair of stars. If you then look at Epsilon Lyrae in a telescope under high power, each of these stars is revealed as another pair of stars; Epsilon Lyrae is known as the "double-double" star, four stars (two pair) appearing as one.

.....Numerous times in the past, I have shaken loose from the constellations of the past merely held on to because, ooh, the ancient Greeks created all of western civilization, big whoop, so as I proposed in my last post, I'm replacing the lyre with the lyrebird. After all, how many of us own harps in this day an age? I myself only have one CD of harp music. Hey, it was at a concert; support artists, art establishes and maintains the common culture! You like culture, right? (If you are next to someone who answered no, remember, engineers are often helpful to society as well.)

NEXT: Telescopic objects in Lyra

The Birds of Summer

.....One of the problems that can keep people from moving from a peaceful contemplation of a dazzling array of stars to finding the dazzling variety of clusters, nebulae, and galaxies that are surprisingly accessible once you make the shift from seeing the sky as a featureless expanse of stars to recognize patterns that will allow you to find wonders hiding in plain -er- slightly assisted sight.

.....Starting in the summer (but lasting until November), three of the brightest stars in the northern sky form a (duh) triangle that covers much of the sky. This "triangle" that first appears in the "summer" sky is called the Summer Triangle because at some point, astronomers got tired of doing things like grabbing a rough pentagon of fourth magnitude stars and calling it "the giraffe"

.....The three bright stars are in three different constellations because the Summer Triangle really does cover a large selection of the sky, and ancient astronomers invented constellations to be able to break the sky into manageable pieces, so they weren't going to invent constellations that tokk up most of the sky. Well, not more than once, anyways. The three bright stars are Altair, Vega, and Deneb, in the constellations of Aquila, Lyra, and Cygnus (the next three constellations I'll write about), and you can use these to do a bit of traveling into the past. Altair, the southernmost star in the triangle, is about 16.8 light years away. This means that it has taken the light from Altair more than sixteen years of traveling through space. The light that reaches us on Friday left Altair about November 12th, 1993.

.....In the northwest, the brilliant star Vega appears to be a step brighter than Altair, but it is actually giving off more than four and a half times as much light into space than Altair does, but Altair is closer. Vega is 25.3 light years away, which mean that Friday's light from Vega left about May 2nd, 1985.

.....The third star, Deneb, is the faintest of the three as seen from Earth, but it actually gives off more than 60,000 times as much light as the Sun does. If we wanted to move Earth to Deneb and get as much light as we do now, we would have to move the Earth to be seventeen times as far away from Deneb as Pluto is from the Sun. Deneb is more than three thousand light years from our solar system, meaning that the light we see now has been traveling through space since 1218 BC, when Ramses II (the Great) was Pharoah of Egypt, and the Trojan War was going on*.

.....These three constellations will be the next three that I write about, Cygnus the swan, Aquila the Eagle, and Lyra the Lyre ... y'know, since two of these three are birds, and since I have felt no compunction about changing constellations, let go ahead and change Lyra to the Australian Lyre-bird, and have these three as as the birds of the Summer Triangle. There are a couple of small constellations that will also show up: Sagitta the arrow, located inside the Summer Triangle, and Scutum, the shield, which I will discuss along with Aquila the eagle, because Aquila has no Messier objects of its own.

* or at least this falls into the range of time in which the original Trojan War took place.

The Moon in the Sky

.....In response to a couple of questions, I've tried to come up with a device that would help one work out when the Moon will rise and set, and what part of the sky it will be in for any given time of day. This is my result. First, start with the base of this ("Lunalabe"? ""? I need a better name for it), a wheel that another, smaller wheel will move in.

.....Once that is done, find a way to attach this smaller wheel so that the two wheels have a

common center. The way that I first did this was to use a paper clip; an alternative would be to go to a craft/scrapbooking store and buy a specialty brad which can attach through the center. Perhaps it would be better to use an eyelet, or something that has less of a chance of ripping - we're really at the end of my know-how on this subject, but you can check out my crude attempt in the photograph below.

.....Here is how this works, if you know the phase of the Moon, or when the new and/or full moon is that month (you can find these on many calendars, plus, I will now begin posting that information at the beginning of each month. For August, 2010:

Last Quarter: August 2

New Moon: August 9
First Quarter: August 16

Full Moon: August 24

The lunar month is 29.5 days long. This means that the time between phases is roughly one week, which we can use to find the Moon between these dates. Consider this Friday, August 20th. This is midway between First Quarter and the Full Moon, so we start by looking on the wheel between the First Quarter and the Full Moon. The Moon between the New Moon and the Full Moon is waxing (increasing), and the Moon between First Quarter and Last Quarter is gibbous, so the phase of the Moon on Friday will be "waxing gibbous". This has a "+9" by it, which means that the Moon (all else being equal) will rise, set, everything, nine hours after the Sun does. If we take as an average that the Sun rises at 6 AM, gets as high in the sky as it is going to get (transits) at noon, and sets at 6 PM, this indicates that on Friday, we should expect the Moon to rise at 3 PM, transit at 9 PM, and set at 3 AM.

.....This is where we also have to look at the outer wheel. Line up the lines representing the direction of the Sun (the wheel works because as far as the Earth and the Moon are concerned, the Sun is so far away that it is not a point to examine in perspective, but a direction) is coming from "August". (This also shows that in late August the Sun is in front of the stars of the constellation of Leo.) Imagining a line from the center of the wheel out to the constellation ring, the Moon on August 20th should be in front of the stars of Sagittarius. Sagittarius has a "-2" next to it, because Sagittarius is far to the south, and so this constellation is not above the horizon as long as the others. (The Sun is in Sagittarius in December and January, and the Sun is not above the horizon as long as it is in later months.) The "-2" means that in this constellation there will be two hours less time above the horizon at rising and setting, so we expect to Moon on Friday to rise at 5 PM, transit at 9 PM (this does not change), and set at 1 AM. If we compare this to the actual times, the Moon will rise at 6:01 PM, transit at 10:30, and set at 3:03. This seems wrong, if you don't take that hated Daylight Savings Time into account.

.....Tell you what, during DST, just shift your predition forward one hour, so our expected times are Moon rise at 6 PM (pretty close), transit at 10 PM (close-ish, I make no promises to be exact), and Moon set at 2 AM (admittedly sketchy - I might need more work on the hour modifiers on the outer wheel). Still though, this first version does provide a decent rough time, and it identifies where the Moon will be in the sky well. You can use this to help learn the constellations along the path of the Sun and Moonin the sky (the zodiac), as long as the Moon is not too bright.

.....On the other hand, if you see the Moon in the sky and you recognize its phase,this can be used to find rise/set times from that as well. This (I certainly hope) will help you find the Moon in the sky, and this will tell you what constellation it is in.

.....Please let me know if there is a feature that you would like the wheel to do that you do not think that it does, or if there is a feature that is too distracting. If you would like to try this, I have the images as two pages in a PowerPoint presentation at this site.

.....SPECIAL NOTE FOR TEACHERS. I use this device in class to try to illustrate the relationship between the Earth, Moon and Sun defines the appearance of the Moon. If you would be interested in something like this, please let me know, and we can compare notes.