Venus Transit in hydrogen alpha light, 5 June 2012
(Credit & copyright: Gilbert A. Esquerdo)
Transit Of Venus 5 June 2012
Seen in projection at the UW Space Place, Madison, WI
View Today’s Venus Transit Online
So you say it’s cloudy where you live today, or you don’t have the proper eye protection required to see the event, but you still want to see the historic Venus Transit?
The Interwebz are here to save you.
A number of online resources are available, including telescopes broadcasting live feeds of the event:
- Live coverage of the event will be available from the National Solar Observatory station at Sacramento Peak, New Mexico beginning at about 6pm Eastern Daylight Time (EDT)
- NASA EDGE broadcasting from Mauna Kea, Hawaii, starting at 9:45pm UTC (5:45pm EDT)
- Las Cumbres Observatory Global Telescope Network will broadcast from Haleakala in Hawaii
- The SLOOH SpaceCamera with images from around the world
- Mt. Lemmon SkyCenter (Arizona) will broadcast video of the transit live starting at 2pm MST (one hour before the transit starts)
- Astronomers Without Borders will broadcast a live webcast, hosted by president Mike Simmons
- The Exploratorium will show a live feed of the transit, with commentary every 30 minutes
- Researchers from University of Barcelona’s Department of Astronomy and Meteorology will broadcast the transit live from the Arctic Svalbard archipelago, the northernmost part of Norway
- The Kwasan Observatory will air the transit live from Japan
- The Appalachian State University will stream a live feed from one of its 11-inch Celestron telescopes
- The Bareket Observatory will broadcast the latter part of the transit live from Israel
- The Sky Watchers Association of North Bengal (SWAN) brings you a live feed of the hydrogen-alpha sun
- The Planet Hunters (part of the Zooniverse citizen science project) will be broadcasting a live feed from their website
- Columbus State University’s Coca-Cola Space Science Center will be broadcasting the transit in many different wavelengths using hydrogen-alpha, calcium-K-line, and white-light solar filters
- Real-time solar image data is available from SolarMonitor.org
- Live images of the Sun in the absorption line of hydrogen-alpha can be found on the Global H-Alpha Patrol Network
- Helioviewer collects many real-time spacecraft images of the Sun
- Sun-Earth Viewer (NASA/Cal-Berkeley) Ground and space-based views
- Solar and Heliospheric Observatory (SOHO)
- Solar Dynamics Observatory (SDO)
- Solar-Terrestrial Relations Observatory (STEREO)
(with thanks to Professor Astronomy and Sky & Telescope for the links)
The Disappearing Black Drop
Observers of historical transits of Venus have observed the black drop effect — but will you?
(This series of images shot from Singapore shows the possibility of a black-drop effect. Credit: Joseph Tey)
“After the 2004 transit of Venus, observers were puzzled by the appearance (or lack thereof) of the black-drop effect, the dark patch that appears to connect Venus with the dark sky past the edge of the Sun, sometimes giving Venus a teardrop shape. The black drop was widely observed and commented on in the 18th and 19th centuries. So why, in 2004, did some people not see it at all?”
“‘Some of it may be a matter of degree,’ says Jay Pasachoff (Williams College). He says his study with Glenn Schneider (University of Arizona) of space-based images of the 1999 and 2003 Mercury transits shows that the telescope’s optics and resolving power are a factor in the black-drop effect. But they discovered that the Sun’s limb darkening— the fact that the Sun’s edge is darker than its center — is another important contributor. ‘So it’s not a surprise that big telescopes that have a better point-spread function don’t show a black drop effect.’”
(The ‘black drop effect’ — an unexpected “neck” of darkness that seems to connect the black sky to the disc of either Venus or Mercury during solar transits — was at times attributed to everything from refraction of light in the atmospheres of those planets to the imagination of observers’ minds. Now we know that at least the effect is real, but it is the result of several factors conspiring together, including imperfections in the way telescopes image light. What will telescopic observers see on Tuesday? -JCB)
(Australian watchmaker F. Allerding recorded the “black-drop” effect as the silhouette of Venus prepared to exit the Sun’s disk on December 9, 1874. He observed through a 3½-inch refractor. CredIt: Institute for Astronomy, Univ. of Vienna.)
Your Viewing Guide to the Transit of Venus
A literal once-in-a-lifetime event occurs this Tuesday, when the silhouette of the planet Venus crosses the visible face of the Sun over several hours. Here’s when and where to see it.
What can you expect to see?
“Venus will take about 6 hours 30 minutes to cross the northern side of the Sun. The line is plotted as seen from Earth’s center. Universal Times (also geocentric) are given for the event’s four contacts: I and II as Venus moves onto the Sun (called ingress), III and IV as it leaves (egress) and for Venus’s deepest encroachment onto the solar disk.” (Credit: Leah Tiscione/Sky & Telescope)
Where will the transit be visible?
“For most of North America, the transit of Venus will begin on the afternoon of June 5th and still be in progress at sunset. Those in western Pacific, eastern Asia, and eastern Australia see the whole show from beginning to end on June 6th (local date). Click here for a larger, worldwide map.” (Credit: Michael Zeiler / Eclipse-maps.com)
How’s the weather going to be?
“Based on statistical averages of daytime clouds during June, the American Southwest, northern Australia, and the Middle East offer the best chances of clear skies for the transit of Venus. Click here for a larger version.” (Credit: Jay Anderson)
Why does it matter where on the Earth one is located?
“Your location north or south on Earth slightly affects the apparent path you see Venus taking south or north across the Sun. In 1716, Edmond Halley realized that measurements of this offset, done by timing Venus’s contacts with the Sun’s edges, could be used to determine Venus’s parallax as seen from Earth and hence the distance to both Venus and the Sun. That in turn would give the correct scale of the entire solar system, which was poorly known at the time.” (Credit: Sky & Telescope)
PLEASE READ this summary of safe solar viewing tips and protect your eyes!
Partial Lunar Eclipse on June 4th, 2012
Everyone keep an eye out for this cool event. It will be visible on the morning of June 4 for North America, but in Australia and Asia it will be the evening June 4. Approximately one third of the moon’s face will be eclipsed. For us here in NZ it will start at 10:00pm, keep an eye out! I know I will.
(Image via weather.gov.hk, and NASA)
This eclipse will largely be an event for the Pacific and Australasia, although the Americas will be able to see some part of it. Information and times for various locations can be found here, here, and here.
On (And Near) The Center-Line: The 20th May annular solar eclipse from Utah
Kanarraville, Utah was very close to the center-line of Sunday’s eclipse, meaning that it was nearest to the center of the darkest shadow cone produced by the Moon as it crossed the face of the Sun. In this image, the disk of the Sun (red) perfectly frames the shadowed outline of the Moon at mid-eclipse. Compare with the photo below, taken from Zion National Park (about 18 miles southeast of Kanarraville) at the same time.
(Credit: G.A. Esquerdo)
The location of the two sites is shown on the map below. The red line is the eclipse center-line; Kanarraville is very close to where the red line crosses the thick orange line indicating Interstate 15. Zion is at bottom-center.
Even though the moon is about 240,000 miles away, a linear difference of 18 miles on the surface of the Earth is sufficient to noticeably shift the apparent position of the Moon in the sky. This becomes crucial in total solar eclipses, when the region in which the eclipse is total may be only a few miles in width.
Annular eclipses occur when the Moon is slightly further away from the Earth than on average; when it is closer than average, the solar disk is completely blocked and a total eclipse occurs. The next annular eclipse is on May 10, 2013.
Solar Eclipse from Kanarraville, UT. May 20th, 2012
Credit: by-tor
May 20th Annular Solar Eclipse From West Texas
(Credit: Rachel Walker/University of Texas/McDonald Observatory)
Astronomy news, recent research results, and pretty pictures from the media along with context, commentary, and explanations for folks who dig this sort of thing. Written by a quasi-professional astronomer affiliated with the University of Texas at Austin.
