Monthly archives: December, 2004

Cloudy Nights

The past few nights here have been completely overcast with not even a break in the clouds.

The other night I went down to Company 7 and picked up two things – a upgraded finder scope that is of the same spec as the one that came with my XT10 (9×50) but this one has a 90° eye piece on it so I no-longer have to make my neck contort to view through the original stright eye piece. Also, the image it shows is not inverted, so it makes maneuvering the scope and matching what I see against the star chars much easier and more intuitive.

I also got a sheet of Baadner AstroFilm for a small project. AstroFilm is a thin polymer sheet that sort of looks like mylar, but it isn't. Its used to make a filter and view the Sun directly with. The stuff sure isn't cheap. An A4 sized sheet of it cost me $30.

So what I'll do this weekend after I finish my New Years Eve hang-over is get out some cardboard and make an arpeture mask for my telescope. I'll size the mask so that it slows my scope down from f/4.7 to somewhere around f/12 and then put this AstroFilm over the opening. With this I can comfortably view the Sun stright on and at high mag and see solar flares and sun spots.


More on Saturn and the Moon

I dragged my scope up to UMBC tonight to get another view of Saturn. Despite the light pollution from Baltimore, I got a pretty good view and studied it for a while. Although my eyes were tearing from the cold, I saw a better picture of the Cassini Division in the rings and the banding in Saturn's atmosphere. I found its moon Titan this time around, and saw Rhea and Dione again. Saturn truly is a sight to behold and its rings are pretty much beyond imagination. Together with its moons, its whole system looks like a grand opal with bright diamonds around it.

Next, I tried to get a better view of the Orion Nebula. Again, I could clearly see the faint teal color of the nebula and this time I also could make out the Trapezium, the three bright stars that shine from within and behind it.

Lastly, I decided to look at the most brilliant object in the sky, our own Moon. I loaded in my 25mm Plossl eye piece and the entire disc of the Moon filled it, and the detail I saw was nothing like I saw before. The Moon isn't quite 100% full yet, so I put in my 7mm Nager eye piece and zeroed in on the dark lower edge. The Rook Mountains greeted me, with their hard, jagged edges contrasted against the pitch blackness of space behind them. Tycho, the massive crater on the bottom part of the Moon was especially nice, with its long tendrils of bright ejecta streaming out from the crater over the bottom quarter. I realized that Tycho is a relatively new crater on the face of the Moon, since its ejecta was streaked across the the dark gray Mares around it. It must have been a fairly cataclysmic impact to cause all that debris to shower so far away from ground zero in such concentrations.

I really can't wait until the weather gets warm enough to make it worthwhile to drive out to areas of less light pollution to observe. I've already decided to bring my scope to Playa del Fuego and the Gaian Mind Summer Festival in the spring and summer. These two events take place in fine, dark areas. Perhaps I'll also give some astronomy lessons as well.


Orion Inteliscope Cable and Adaptor

Alright, so now I figured out the RS-232 pinouts on the telescope control computer interface. On its 4 wire RJ-11 plug, I found that Pin-1 was xmit, Pin-2 was recv, and Pin-3 was ground. Pin-4 is apparently unused. Bare basic RS-232 with no handshaking or CTS/CTR. I managed to work this backwards and figure out the wiring of a RJ-45 to DB9 adapter I had on hand, and then one Blue Moon beer later I had figured out how I should wire this RJ-11 -> RJ-45 -> DB9 adapter and did so successfully.

Now as I turn and raise/lower my telescope mount, it talks to my laptop which then displays, on screen, what it's looking at in the sky (not an actual picture of what it sees, mind you, but a simulated representation.) Full sightless tracking in full effect. Now to get some motors on this sucker.

Ain't technology sumptin'. This coolness is right up there with the invention of toilet seats.


The Celestial Poles

Rob Carlson responded to my post last night about Precession and asked about the Northern Celestial Pole (NCP) I mentioned. Explaining this deserves its own entry, so here we go.

We all know that Earth rotates on its polar axis. This gives us night and day. This makes the Sun rise in the east and set in the west, as well as the stars and moon at night. Basic stuff.

The Celestial Poles (there's a North and a South one) are points in the sky that we, standing on earth, see all objects in the sky (the Sun, the Moon, the stars) revolve around. So, if we pointed a camera directly at the Northern Celestial Pole and held the shutter open for a few hours, we would see that the stars made a circular pattern around this point, giving a picture that would look like this:

The stars rotating around the NCP

The star Polaris, the "North Star", is almost exactly positioned at this point in the sky (In the picture above, that small arc near the center is Polaris). There's a Southern Celestial Pole, too, but we in the Northern Hemisphere don't see it, just as people in the Southern Hemisphere don't see our Northern Celestial Pole and Polaris, they see their own. But we up here are lucky, we have a star (Polaris) that's almost right on the NCP. The people down under don't have a "South Star" because there's no star close enough to the SCP to be called that.

To help visualize this movement, I made a movie. In this movie, we are looking at the point in the sky called the NCP. You will see the star Polaris right next to it (within 1 degree.) I will then speed up time so you will see a full 24 hour rotation in the movie.

You can see this movie (Quicktime Format, 1.2MB) by clicking here.


Hey baby, what's your sign?

I'm having a tough time trying to fall asleep tonight, so I figured I would write something here.

Recently, as I educate myself on all things astronomical, I came across an interesting bit of info on the Zodiac. As you probably know, the Zodiac was originally laid out 2,600 years ago with the twelve signs we're all familiar with. Each sign represents the constellation that the Sun travels through (more or less, it's measured in 30° increments) over the course of a year. So, for example, 2,600 years ago, the Sun was in the constellation of Aries from March 21 – April 20. Then, as the earth moves in its orbit, the Sun would appear to be in the constellation of Taurus, and so on.

But over the 2,600 years, things have changed astronomically speaking. Due to a phenomena of orbital mechanics called Precession, Earth's view of the Sun has changed slightly, but just enough to add a 13th constellation to the original Zodiac, and this is the constellation of Ophiuchus. Ophiuchus now sits between Scorpio and Sagittarius, and shifts the dates of all other Zodiac signs accordingly. If the Zodiac were revised to fit today's sky, the chart would be like so:

Capricorn – Jan 20 – Feb 16
Aquarius – Fb 16 – Mar 11
Pisces – Mar 11 – Apr 18
Aries – Apr 18 – May 13
Taurus – May 13 – June 21
Gemini – June 21 – July 20
Cancer – July 20 – Aug 10
Leo – Aug 10 – Sept 16
Virgo – Sept 16 – Oct 30
Libra – Oct 30 – Nov 23
Scorpio – Nov 23 – Nov 29
Ophiuchus – Nov 29 – Dec 17
Sagittarius – Dec 17 – Jan 20

Interesting, eh? So if you were born on December 8th, you're no longer a Sagittarius. You're now a Ophiuchus. Of course, modern astrology sticks to the original Zodiac.

So what's Precession? Precession was first discovered by the classical astronomer Hipparchus in the second century BC by comparing star charts he made to those made hundreds of years before him and noting how the sky "shifted". Earth is not a perfect sphere. Because it rotates, the centrifugal force makes Earth bulge at the equator (Earth's equatorial diameter is 13 miles larger than its polar diameter.) The Moon, Sun, and to a much lesser extent, other planets, pull on this bulge. This gravitational tug of war causes Earth to precess (wobble) on its rotating axis (much like how a gyroscope wobbles but doesn't fall over). Over the course of 25,800 years, the wobbling makes Earth's polar (rotating) axis trace a complete circle. This shifts the regular position of the stars we see, and so we now see the Sun go through an additional constellation.

Keep in mind that all other stars we see shift in the same manner, in the same direction and at the same rate. Polaris, our "north star", is currently about 3/4° from Earth's northern celestial pole. 600 years ago, it was 3.5° away from the NCP. 2000 years ago it was 12° away from the NCP and couldn't really be considered the north star. In fact, back in 2,700 BC, the north star was actually the star Thuban, which as a result held a great importance in ancient Egyptian theology. Today, Thuban is about 25° from the NCP.


First Light

In the very early hours of December 25, 2004 at approx. 1:30am at 39.39875º N, 77.10772º W, I made first light with my new Orion XT10i Inteliscope dobsonian telescope. The sky was very good with little surface winds with a temperature of 19 F, and a 13.28-day old waxing gibbous moon.

Orientation stars for alignment of the telescope computer were Betelgeuse (Orion) and Mizar (Ursa Major). Both were easily found in the 7 degree FOV finder scope. Betegeuse shown a pale orange color, owing to its status as a dying red giant star 429 light years away. Mizar, which is the middle star of the "Big Dipper" handle, is a small, bright binary star.

First target after orientation was the Orion Nebula, NGC 1976 and its companion, De Mairan's Nebula, M43. I zeroed in on NGC 1976 with ease, and was amazed at how spot-on the Orion Intelliscope computer was about giving directions. With the 10mm Plossl eye piece installed in the telescope, I could see both nebulas at once. The nearly-full moon's light blocked out a lot of color, but I could clearly make out the faint blue-green clouds of both nebulas, and if the moon weren't so bright, I probably would have seen some red, too.

The second target was Saturn, which was high in the easten sky just below the stars Pollux and Castor. Again, supplied with the right date, the Intelliscope system allowed enough accuracy to get Saturn in the finder scope, and the resulting view through the 10mm Plossl was astounding. The rings, with their Cassini division, were clearly discernable, and I could even make out faint color bands in the southern hemisphere of the planet. Several moons were also visible as bright points. I could clearly make out Dione and Rhea.

Because it was 19 degrees F out, I opted for one last target, and that was… a plane! Yes, suddenly, a bright flickering light appeared on the western horizon and quite low. I could not make out what it was, so I swiveled my telescope around and found the object in the finder scope, and then got a look at it through my eye piece. It was a jet liner. Flying straight at me. Its head-on profile filled my eye piece and I could make out the bright landing lights together with the red and green navigation lights on the wing tips. Because the plane was flying towards me, I could keep it targeted in my eye piece's field of view for a relatively long time before having to adjust the scope.

Well, there was now a visible "pool" of frost on the body of the telescope near the eye piece (from my breath), so it was time to go inside and get warm. This was a wonderful "first light" and I can't wait for the next clear night, where I'm sure I'll be outside again, ignoring the cold to see the heavens above.