The Astronomy Files

New Star Atlas

Years ago I bought Star Atlas 2000 and have used it sparingly ever since.  I say sparingly because most of the time I use my laptop and either MegaStar or The Sky.  But since I installed the pier mount in my backyard, I've been looking for something that I can just grab and go with if I want to observe for only an hour or so without dragging out the laptop.

So, I ordered Sky and Telescope's new Pocket Star Atlas and it arrived yesterday.  Actually I was surprised that Fed Ex delivers on Saturdays but I guess they're competing with UPS.

Anyway, it's exactly what I was looking for.  Sky Atlas 2000 is OK but the charts aren't well arranged and, when I bought it, I had to go through and draw the constellation stick figures and note which chart joined which.

Pocket Sky Atlas is much better.  It's arranged by right ascension in 3 hour blocks.  The first pages cover RA 00 to 03 hours from declination 0 degrees north to 0 degrees south.  It also notes which block is viewable at what time of year.  There is, of course, overlap but it gives an observer a general idea what's up at what time.

Even though I was very tired from a woodworking project I spent all day on, I went out to the scope for an hour last night and tried the charts.  I must say it was nice to have something only 6" x 9" that I can hand hold at the scope rather than the huge charts of Sky Atlas 2000.  Granted, it doesn't have the magnitude depth of SA 2000 since star mags only go to 7.5 but in my light polluted area, that doesn't matter.

All in all, I'd say this is a winner and others agree.

Mercury Transit

Didn't have time to post this yesterday but I observed the Mercury transit and shot some images during the first 30 minutes or so of the event.

I was most interested in a curious thing that occurs at first and second contact (also at third and fourth but the Sun was behind the trees by then).  First contact is defined as the moment the planet blocks the limb of the Sun.  Second contact is when the opposite side of the planet clears the limb.  There is an associated phenomena that is a strange kind of distortion of the view of the planet known as the "black drop effect".  At first and second contact (and third and fourth as well but the Sun had set by then) it appears to stretch a bit, causing it to look like a drop of liquid.  Just keep watching and you'll see it happen.

I decided to not bother with imaging past the first half hour.  After all, when you've seen one black dot, you've seen 'em all.  I tried posting an image of the effect here but Typepad does some horrific things to images when they are uploaded into blog posts.  I put together a flash animation that shows Mercury moving across the Sun and it can be found here.  Just keep watching and you will see the planet move across the Sun.

This is my imaging set up that I used to take the pictures.  I used a Takahashi FS-102 scope with a Nikon D70S mounted on a flip mirror.  The flip mirror let me view the transit without having to use the viewfinder in the camera.

Update: Here's a really good movie in H Alpha light showing a large portion of the transit.  It's only 2 minutes long but actually covers a 4 hour period.  The producer is Rainer who frequents the Losmandy user group.  Don't know if that's his first name or last name.

Stupid Space Tricks

Not to be outdone by brainless astronomers, an ad agency wants to put up a suborbital billboard.

Astronomers Without Brains

And I always thought this guy was really smart.

Observing The Moon

The best time to observe the moon is between the time when it's new and first quarter.  Tonight it's only a couple of days from full but the evening was so nice I decided to spend some time gazing at it.

When you observe Luna through a big telescope the first thing you notice is that, after a couple of minutes looking at it, you go blind in your observing eye.  It's so bright that your pupil stops down and, if you glance away from the eyepiece, you see nothing out of that eye for quite some time.  In fact, it takes several minutes for my eyes to recover and to regain a modicum of night vision.

If the moon is not full, there are features illuminated at an angle which provides a sort of modeling to certain parts of the surface.  Mountains and crater rims cast shadows and these shadows provide dimension to what you are observing. 

I didn't have any grand plans for tonight, just wanted to scan around the orb at high power for a while.  As I moved my scope around the terminator, I ran across a very interesting complex of craters, rilles, and mountain chains.  The image contained in this post was lifted from a program called Virtual Moon Atlas and, even though it is quite accurate, portrayal of some surface features is a little off.

I've marked the three prominent features in this complex (click on the image to make it bigger).  The crater Aristarchus, about 24 miles in diameter, is considered to be the brightest feature on the face of the Moon.  It is sometimes visible in the earthshine of a young moon and easily seen with the slightest magnification.

Vallis Schroter is a 97 mile long rille that is unusual because of the circular path it takes on the surface.  It's beginning is marked by a crater with an unusual name:  Head of Cobra.  This moniker apparently refers to the snake-like appearance of the rille.

Montes Agricola is a mountain chain about the same length as Schroter, 97 miles.  What's unusual about it is that during certain times a shadow is cast across the mountain by Dorsum Niggli, a "wrinkle ridge' just north of Agricola.  If you watch this shadow long enough, it moves (quite slowly but it moves nevertheless), showing the change in phase of the moon right before your very eyes.

Tonight and possibly tomorrow afford the last days of good viewing for this Moon cycle until it gets past full phase and starts to wane.  But observing then becomes a late night or early morning practice.  For now I think I'll stick with the waxing moon.

Mercury Transits The Sun

When a planet crosses in front of the Sun, it's called a "transit".  The most recent and most heralded transit was when Venus crossed in front of the Sun back in 2004.  Unfortunately for us, it was not viewable in southeast Texas.  But this month we will be able to see the transit of another planet, Mercury.  On November 8, 2006, Mercury will cross the sun's disk, spending several hours as a tiny black dot on the face of old Sol.  Since Mercury is very small, it cannot be seen without telescopic aid.  WARNING!  NEVER LOOK DIRECTLY AT THE SUN AND ESPECIALLY NEVER USE A TELESCOPE OR BINOCULARS TO VIEW THE SUN WITHOUT A PROPER FILTER! 

For observers in the central time zone, the transit begins at 1:12 p.m.  More info here.

Leonids 2006

Unlike Comet Halley which a person will probably only see once in a lifetime--if then--55P Temple-Tuttle swings by our part of the solar system once every 33 years.  But each November we get a taste of its leftovers when the Leonids meteor shower lights up the sky with remnant dust particles.

This year is supposed to be a fairly good one for meteor rate, sort of short and sweet.  Too bad we're not going to see much here.  Predictions are for good rates in parts of Africa and Asia.  North and South America may get a few blips but you'll have to stay up late if you want to see them.  November 18 is the big day, er, night.

New Life For Hubble

NASA has decided to re-fit the HST during a mission in 2008.  Hubble has probably done more to advance science than any other machine ever built by man.  There is a replacement waiting in the wings.  Hopefully, this work will keep astronomers in goodies until the JWST can launch and come on line.

Echos of Light

V838 Monocerotis is a very strange animal.  It's officially called a variable star but it's also one that is still in formative stages and does weird things like periodically making huge jumps in magnitude.

In 2002, V838 Mon went into outburst and increased in magnitude to become a staggering 600,000 times brighter than our Sun.  In addition, there's lots of dust around the star and, when it goes into outburst, the dust is excited by light from the star, causing what some call a "light echo" caused by the delay between light that comes directly to Earth and scattered light from the interstellar dust. 

As an example of how this star can vary, here's a data page from the AAVSO web site showing that it changed magnitude by a factor of better than 1 (brightness change of  more than 2.5) between October 1 and October  9, 2006.  The chart shown here gives an indication of how much change has occurred in past.  You can see that it's been all over the place.

And here is a comparison image from Hubble showing changes between November, 2005 and September, 2006.

Lots more stuff here.

How Do Flamingos Eat?

Leaving the realm of astronomy for a moment and exploring a scientific "hard question."