UPDATE:  The NHAS has posted their preliminary observing locations and maps:  http://nhastro.com/events/transit.php

This June 5th, we have an opportunity to see a rather rare astronomical event, the transit of Venus, when the planet Venus gets between our Earth and the Sun. The result is that we can see the small, round dot of Venus’ silhouette traversing across the bright disk of the Sun. This event has both tremendous scientific and historic significance in astronomy, but it also has its dangers.

The Sun is bright, something we all know. We shouldn’t look at it without proper protection, namely solar filters. One should definitely NOT look at the Sun through a telescope unless one employs a full aperture solar filter which has been approved for visual solar observing. Failure to adhere to this warning means instantaneous and irreversible damage to your eyes.

• Do not employ dark glass for a solar filter.
• Fogged film is not an appropriate solar filter.
• Dark sunglasses are not appropriate solar filters.
• Welding glass used at the eyepiece of a telescope is NOT a safe solar filter.

If you are interested in seeing the transit using safe equipment, and you are not sure what to purchase, you have some options:

• Visit your local astronomical society or planetarium and ask the astronomers there for equipment suggestions.
• An affordable solution to see the transit without optical aide would be to purchase some “Eclipse Glasses” from a source like Amazon. This one comes in a package of 5:  HERE.  WARNING!!!  DO NOT USE THESE IN COMBINATION WITH BINOCULARS OR OTHER UNFILTERED OPTICAL SYSTEM. These cannot withstand the light and heat concentration put out by optical instruments. These are for wearing alone.
• Many local astronomy clubs, societies and associations will be setting up equipment for the public to use in order to view the event. The New Hampshire Astronomical Society is doing just that and will post information at http://www.nhastro.com as they prep for multiple observing sites throughout the state on the afternoon of June 5th.
• From the east coast (New Hampshire), the Sun will be setting as the transit begins. Some observatories, including the one at Phillips Exeter Academy will not be able to see the Sun through trees and houses which will obstruct the view. In these cases the observatory will remain closed, and a portable observing location would be set up elsewhere at a higher elevation with a clear westerly view. Stay tuned to your local club’s/observatory’s websites for more details.

Historical Significance:

Transits were one of the earliest observational methods used to determine an accurate measure of the Astronomical Unit, the average distance between the Earth and the Sun. Using two widely separated observing stations and precise timepieces, observers would note the time difference between the start and end of the transit. Using then the mathematics of triangles (parallax) and Kepler’s Laws of Planetary Motion, the distance could be calculated.

The earliest observation of this type actually involved the planet Mercury transit of the Sun in 1676. A rather famous astronomer (you know the name!), Edmund Halley, made observations from St. Helena. One other set of observations was made elsewhere, but the mathematics proved to show some serious inaccuracies. In 1761 (and by this time Halley had passed away), there was a Venus transit. Many sites were established to observe the event. In 1769, another Venus transit was observed, and also created a large scientific collaboration between countries. This was also the first event which marked Captain James Cook’s initial voyage through the Pacific. Future transits were then observed, the last in 2004. The next one will be in 2117 (December 10-11), so this event in June 2012 will be the last we are able to see in our lifetimes.  To help you plan your transit, see the two images below. The first is from the Wikipedia article Transit of Venus, 2012. The second comes from the NASA Eclipse Website.

From: http://upload.wikimedia.org/wikipedia/commons/6/6b/VenusTransit2012-Map-2.gif

From: http://eclipse.gsfc.nasa.gov/transit/venus/Sun2004+2012-2.GIF

There are plenty of nearby astronomical objects to investigate with a small telescope, but one of the most insidious problems which gets in our way is the issue of “seeing conditions”. When objects on the ground are heated by sunlight during the day, they then radiate throughout the night causing what astronomers call poor seeing conditions.  One can look at the moon or Saturn and see a wavy image one second, only to be followed immediately by a mighty fine and perfectly sharp image of the object. What to do?  Enter modern technology!  A method that was originally developed for the Hubble Space Telescope and then further adapted for amateur use, the drizzling method has caught on by storm. One can even download freeware to try it out:  Registax, which actually does a lot more than simple drizzling.  In the Observational Astronomy class, we actually try this out using the humble webcam as an imager. Taking thousands of video frames, the Registax software takes the best of the images then aligns and averages them together to make one much much better image. This last week we did just that, and here are just a couple of results. All images were taken with a C11 SCT and a ToUCam-II Philips webcam.

Now, you might be thinking, yes, ok, those are fine images, but WAIT, there’s more!  These were taken in the early evening in the spring here in Exeter, NH. The diurnal variation can be as much as 40 or 50 degrees F!  There is a lot of post-sunset heat coming up off those rivers, buildings and parking lots!  This is the video of Saturn from which we captured the frames to make that one sharp image. This is what you would have seen if you were looking through the telescope in real time.

Astronomers use some interesting terminology: phrases such as “in opposition” and “at greatest elongation”. What do these phrases mean, after all? One is of particular note right now: “Saturn is at opposition.”

On April 15th, the planet Saturn will be located directly opposite the sun in the sky. They will be 180 degrees apart. This means that one could draw a line from the Sun, to the Earth, then right out straight to Saturn. This is a good thing for those interested in seeing the ringed world (or any planet in opposition). Planets at opposition are at their closest point to Earth and are at their brightest and largest apparent size.

The opposite is true for planets at “conjunction with the Sun.” Things in conjunction are placed in the same location in the sky from our vantage point. If Jupiter was at conjunction with the Sun, then it would be behind it and invisible to Earth-based astronomers.  The planet Jupiter in conjunction would also be specifically in superior conjunction, which means it’s on the far side of the Sun, since it can never be between the Sun and Earth. Planets like Mercury and Venus can be in superior conjunction or in inferior conjunction, when it is between the Sun and the Earth.

(image Wikipedia Commons)

For those inferior planets like Mercury and Venus, they have no way to reach an opposition position to Earth. They do however reach a position furthest from the Sun in the sky, and astronomers call that the point of greatest elongation. Planets at greatest western elongation appear to rise in the east just before the sun.  Planets at greatest eastern elongation set in the west just after the sun sets.

Other things can be in conjunction as well. A classic example would be the lovely conjunction of the planet Venus and the star cluster, the Pleiades, which occurred last week.  Those interested should definitely see this image of that event: APOD Venus Pleiades Conjunction.

Such a clear night tonight, and it was the first day of classes for the spring term. The Observational Astronomy (Astro-3) class came out to peruse the various telescope types, look at the insides of a Schmidt-Cassegrain catadioptric, and then check out a bright comet through the scopes. Visually, Comet Garradd was not all that striking, appearing as one of the ubiquitous fuzz-balls that we all know and love in eyepiece astronomy. We got the robotic dome going, and that makes a big difference. Here is a one minute integration through a V filter of the comet using the robotic telescope.

If you come to this site routinely, you might have seen the new menu option at the top of the page, a link to the All Sky Camera. This past week, I have spent a number of hours out at the robotic dome working to install drivers and fix odd electrical shorts in order to bring this imager to life. Here it is! The PEA All Sky Camera is a reality and is available online now. The unit is an interesting and compact design. Inside an acrylic-domed metal housing is a video camera that is permanently mounted to a wide field lens. The lens has two controls: focus and focal length (zoom). There are three other goodies also mounted inside the dome: a small fan, a resistive heater unit, and a PC board to which those prior items are connected, presumably a thermostat controller or something similar.  Below is an image taken on March 9th. You can see Orion to the left (South). North is to the right, west to the bottom, and east is at the top of the frame).

The camera’s software also has the ability to take the snapshots and string them together to form a video, saving a new time lapse video at the end of each day (Universal Time day for this imager). Below is the first video taken while the camera was being installed, focused and mounted outside under the sky.

Those of us living at high or mid level latitudes might be interested in seeing the aurora. With the sun entering into another of its 11-year-high cycles, there has been a lot of activity, and even some press about things such as geomagnetic storms and coronal mass ejections. If you are interested in more, these links will help you monitor what we call “space weather” and allow you to catch an aurora in action!

Spaceweather.com: The main site for all news about space weather. Check here for daily, and sometimes hourly postings about conditions.
3-Day Estimated Planetary K Index: The K Index is a good indicator of the size of auroral ovals here on earth. In New Hampshire, we have to reach a 6 or 7 before we see aurora. Larger values allow people further south to see them.
Interplanetary Magnetic Field Plots: Wondering how the magnetic fields are changing out in space?
OVATION Aurora: A new in-development tool for auroral visibility prediction.

Good luck with your quest! Bring a warm coat and a digital camera. If you see any aurora, send in pics!

Driving Intellectual Curiosity Through the Roof from Phillips Exeter Academy Alumni on Vimeo.