Transit of Mercury
For more information, see the Sky & Telescope article at http://www.skyandtelescope.com/astronomy-news/observing-news/get-ready-for-may-9th-transit-of-mercury-041320162/.
Photo of transit added Monday evening. This photo was taken with the 5-inch refractor attached as a finder on PMO’s 24-inch telescope. Note Mercury to left of center and a sunspot group to right of center.
On Monday morning, May 9, from sunrise until about 11:40 a.m., the planet Mercury will appear as a small black dot moving across the face of the Sun, an event known as a “transit.” In our solar system, only Mercury and Venus can transit the Sun as viewed from Earth. Some of you recall the June 2012 transit of Venus, which won’t be repeated for about a century. After Monday’s event, Mercury will transit again on November 11, 2019, and then not again until May 7, 2049 as seen from the U.S.
Solar viewing is dangerous and can result in permanent eye damage. Please DO NOT attempt to view this Monday’s event directly unless you have the proper equipment and know how to use it safely. “Eclipse shades” sold for solar eclipse viewing are not safe when used with binoculars or telescopes of any kind, such as would be required to see Mercury because of its small size compared to the Sun. (Save the shades for the August 21, 2017 solar eclipse instead.) Indirect viewing is possible, using a small scope (such as a spotting scope) to project the Sun’s image onto a sheet of paper. If you attempt this method, use the Sun’s shadow for alignment and NEVER look into the scope when pointed anywhere near the Sun. There is more information in the above-referenced article.
Images and video of the Mercury transit will be available on several Internet sites. At PMO, weather permitting, there will be a couple of properly-filtered telescopes setup to view the transit. Please keep in mind that PMO does not offer public night sky tours until Memorial Day weekend, Friday-Saturday May 27-28, so you should not expect a tour on Sunday or Monday evening before or after the transit, even though the campground is open.