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'Casts, eclipses, transit of venus, venus, Venus Express

Things that Block Light

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Eclipses and Transits and More Eclipses, Oh My

A partial phase of the annular eclipse, shot through solar filter material using a Sony Cybershot. Copyright 2012 Carolyn Collins Petersen.

It’s been a banner couple of weeks for interesting celestial events. First, like many folks, I got to see the annular eclipse of the Sun on May 20th.  We went to southern Utah to get a clear view of the Moon slipping between Earth and the Sun and almost (but  not quite) blocking out all the sunlight. What we saw was a pretty amazing “ring” of light.  I took a few pictures, like the one here, but mostly I just sat and watched it.

We’ve chased a few eclipses now (we’re four for six), so instead of running around and trying to get the best pictures and video, we like to sit and watch. Oh, we did do some automated photography — just let the camera and timer do all the work.  But, mostly we watched. And were rewarded with a cool view that doesn’t come along very often.

In the national park where we viewed (Kolob Canyon, part of Zion National Park), we talked with various people who had driven over from California or Las Vegas or Colorado, and everyone seemed excited about the eclipse.  There were a few telescopes and cameras with solar filters set up, and a fair number of people using the pinhole projection method of viewing the eclipse. So, I was gratified to see that the campaign of “NEVER LOOK DIRECTLY AT THE SUN WITHOUT PROTECTION” was paying off.  It’s common sense, but still, in the heat of an eclipse sometimes even seasoned veterans forget the rule and take a peek, risking their eyesight forever.

The next big event is the Transit of Venus, which occurs June 5/6 (date depends on where you live), when Venus’s orbit will take it across the face of the Sun for several hours.  These don’t occur very often; they happen in pairs every hundred or so years, so the next one after this one will be in the year 2117.  If you’re inclined to take a look, the same rules apply: don’t look directly at the Sun, use proper filters (NOT SUNGLASSES), and enjoy!  There’s a ton of information out there about the transit, so if you want to know more about it, go here, or  here. I even talk about it in my monthly edition of “Our Night Sky” for Astrocast.TV, which you can watch below.

Finally, there’s a little bit of a lunar eclipse occurring tomorrow June 4th.  The best places for viewing this eclipse will be in and near the Pacific Ocean, according to the folks at eclipse.nasa.gov.  However, people in the Americas will see part of it, as will people in eastern Asia.  If you want to watch as part of the Moon slips through Earth’s shadow, get more information at the link above.

It’s kinda cool that three events that are the result of sunlight being blocked by celestial objects are occurring so close together. There’s nothing magical about it, but there is something fascinating to watch, so check out the transit and the eclipse (if they’re visible where you live).  Participate in observing!  That’s what astronomy’s all about!

 

 

hst news, Hubble Space Telecope, transit of venus

Sic Venus Transit Solis

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Hubble Spacium Telescopium Vigilabo

There’s this event coming on June 5/6 called the “Transit of Venus” and as I read about it, the Latin translation of it jumped into my head. My mind’s funny like that. Sic Transit Gloria Venus and all that.

So, what’s it all mean? The Transit of Venus is when the planet Venus will move in its orbit between us and the Sun in a sort of mini-eclipse.  It happens very rarely. In fact, after this one, there won’t be another transit of Venus as seen from Earth until the year 2117.

This mottled landscape showing the impact crater Tycho is among the most violent-looking places on our Moon. reveals lunar features as small as roughly 560 feet (170 meters) across. The large "bulls-eye" near the top of the picture is the impact crater, caused by an asteroid strike about 100 million years ago. The bright trails radiating from the crater were formed by material ejected from the impact area during the asteroid collision. Tycho is about 50 miles (80 kilometers) wide and is circled by a rim of material rising almost 3 miles (5 kilometers) above the crater floor. The image measures 430 miles (700 kilometers) across, which is slightly larger than New Mexico.The image was taken in preparation to observe the transit of Venus across the Sun's face on June 5-6. Courtesy NASA/ESA/STScI

As you can imagine, such an event presents some cool scientific opportunities.  One of them will be for the Hubble Space Telescope, believe it or not.  Hubble, as you may know, can’t look directly at the Sun, and it has a heck of a time looking at Venus simply due to logistics, as well as brightness. It can look at the Moon, and for this reason, astronomers have come up with an ingenious method to ‘watch’ the Transit of Venus by using the Moon as a sort of “mirror”.  They tested it, coming up with the image below.  This type of observational technique isn’t new. It’s very similar to one being used to sample the atmospheres of the giant planets as they pass in front of stars as seen from our point of view on Earth.

For the Venus observations, since astronomers already know the chemical makeup of its atmosphere, they’re going to test this technique on a planet they “know” to see if it can be used on the atmospheres of distant planets around other stars. If it works the way they think it will, then it could help them tease out the very faint fingerprints of the atmosphere of an Earth-like planet, even one that might be habitable for life.

During the transit, Hubble will snap images and perform spectroscopy, dividing the sunlight into its constituent colors, which could yield information about the makeup of Venus’s atmosphere. Hubble’s main instruments will get a workout in this test.  The telescope’s Advanced Camera for Surveys, Wide Field Camera 3, and the Space Telescope Imaging Spectrograph will concentrate their attention on wavelengths of light ranging from infrared to ultraviolet.  The whole operation will take seven hours starting before the transit begins and lasting until well after it ends. Because the astronomers only have one shot at observing the transit, they had planned a practice run to see if their idea would work, which included the test observations of the Moon that resulted in the image above.

This is one of those experiments that’s so elegant and cool because it demonstrates the many-faceted ways that astronomers can study objects. You don’t always have to look directly at something; sometimes indirect observations  get you to the same place. And, that’s glorious!

If you want to do a little transit-viewing yourself, visit the Transit of Venus page for details on safe viewing (because the Sun’s involved, you really have to be careful… and NEVER look directly at the Sun. With that caveat, I recommend you check it out. This is the last time this century sky watchers can view Venus passing in front of the Sun and it’s just one of those cool things you can brag about at the next family picnic or company party.