Archive for June, 2012
Sometimes, instruments that are not specifically designed to observe the Sun can see something from the Sun. This was the case with Fermi, a gamma ray telescope operated by NASA. Its primary mission is to study the most energetic features and events in the Universe, such as supermassive black holes and the merging of neutron stars. Sometimes, however, the Sun makes an appearance in Fermi data. The following GOES X-class flare on March 7th, 2012
was an intense source of gamma-rays. SDO-AIA is not designed to observe gamma-rays. However, Fermi saw the gamma rays from this event. For a great explanation of what Fermi saw from the Sun, check out the following video.
The movie below shows the PROBA2-SWAP view of the transit so far:
Venus appears to swing north and south in this movie – this was predicted by the operators of SWAP at the Royal Observatory of Belgium Solar Data Influences Center. It is caused by the orbit of the PROBA2 spacecraft around the Earth creating very different points of view of at different times in the orbit.
More movies to come!
Alongside of our coverage of the last Transit of Venus that most of us will get to see (the next one will be in 2117 for those of you who are particularly ambitious!) we are also launching a new online discussion forum: community.helioviewer.org.
Here, users can share interesting features and events they find and get help identifying solar phenomena. In addition to forums on topics such as “transits and eclipses” to “coronal mass ejections,” we also have other sections including “solar physics” and “heliophysics” for anyone interested in learning more about the science that goes on behind the pretty pictures and movies.
Check it out and let us know what you think!
Here are some of the many excellent videos made by Helioviewer.org users of the Transit of Venus seen by AIA…
EIT has been taking special images of the transit. From the vantage point of SOHO, Venus does not appear to cross the disk of the Sun. In the image below, the EIT image is in green.
Just to the north you can see the dark disk of Venus.
More to come with AIA, very soon!
We hope you have the opportunity today to view this event safely. Due to expected heavy traffic to NASA websites concerning today’s Transit of Venus, we are reproducing in full the safety advice given at NASA’s safe solar viewing site. We will carrying images as they become available to us, as will many other sites, including live streaming from Mauna Kea, Hawaii.
Safe Solar Viewing
The transit of Venus is a rare and striking phenomenon you won’t want to miss— but you must carefully follow safety procedures. Don’t let the requisite warnings scare you away from witnessing this singular spectacle! You can experience the transit of Venus safely, but it is vital that you protect your eyes at all times with the proper solar filters. No matter what recommended technique you use, do not stare continuously at the Sun. Take breaks and give your eyes a rest! Do not use sunglasses: they don’t offer your eyes sufficient protection.
Fantastic Viewing Resources
- Dr. Doug Duncan, astronomer, Department of Astrophysical & Planetary Sciences, Univ. of Colorado and Director of Fiske Planetarium
- Definitive advice on viewing the sun safely; by B. Ralph Chou, MSc, OD.
- Six ways to see the transit!; by Chuck Bueter
Viewing with Protection — Experts suggests that one widely available filter for safe solar viewing is number 14 welder’s glass. It is imperative that the welding hood houses a #14 or darker filter. Do not view through any welding glass if you do not know or cannot discern its shade number. Be advised that arc welders typically use glass with a shade much less than the necessary #14. A welding glass that permits you to see the landscape is not safe. Inexpensive Eclipse Shades have special safety filters that appear similar to sunglasses, but these filters permits safe viewing. Eclipse shades are available through retailers listed at http://www.mreclipse.com/Totality/TotalityApC.html under “Solar Filters.”
Telescopes with Solar Filters — The transit of Venus is best viewed directly when magnified, which demands a telescope with a solar filter. A filtered, magnified view will clearly show the planet Venus and sunspots (http://skyandtelescope.com/observing/objects/sun/article_101_1.asp). Never look through a telescope without a solar filter on the large end of the scope. And never use small solar filters that attach to the eyepiece (as found in some older, cheaper telescopes.) See “Solar Filters” as cited above for retailers.
Pinhole projectors — These are a safe, indirect viewing technique for observing an image of the Sun. While popular for viewing solar eclipses, pinhole projectors suffer from the same shortcomings as unmagnified views when Venus approaches the edges of the Sun. Small features like the halo around Venus will not likely be discernible. Pinhole projectors and other projection techniques are at http://solar-center.stanford.edu/observe/.
Related projection methods — One viewing technique is to project an image of the Sun onto a white surface with a projecting telescope. http://www.skyandtelescope.com/observing/objects/sun/Solar_Projection.html and http://www.astrosociety.org/education/publications/tnl/05/stars2.html. Others follow:
- The Exploratorium demonstrates how to view a planet in transit safely by projecting the image with binoculars. http://www.exploratorium.edu/transit/how.html.
- The Sunspotter telescope viewer (recommended for younger viewers) is commercially available from Learning Technologies Inc. at http://www.starlab.com.