Featured Research

from universities, journals, and other organizations

Rare Transit Of Mercury

Date:
November 6, 2006
Source:
Williams College
Summary:
When Mercury goes in front of the sun on Wednesday, Nov. 8, a rare event, scientists from Williams College and the University of Arizona will be observing it from vantage points on earthbound mountains and with orbiting spacecraft.

This figure shows the path of Mercury across the Sun's disk on 2006 Nov 08. Mercury appears only 1/194 the size of the Sun, so its tiny disk will require a small telescope to see (using a special solar filter to protect the eyes).
Credit: Image courtesy of NASA/Goddard Space Flight Center

When Mercury goes in front of the Sun on Wednesday, Nov. 8, a rare event, scientists from Williams College and the University of Arizona will be observing it from vantage points on earthbound mountains and with orbiting spacecraft. Jay Pasachoff of Williams College (Williamstown, Massachusetts) and Glenn Schneider of the Steward Observatory of the University of Arizona (Tucson, Arizona) will be perched at the University of Hawaii's solar observatory, at the rim of the giant Haleakala crater at an altitude of 10,000 feet on the island of Maui. (The crater is wider than Manhattan island and deeper than Manhattan's tall skyscrapers.) Separately, Williams College's Bryce Babcock and solar astronomer Kevin Reardon from the Arcetri Observatory in Florence, Italy, will observe the transit from the Sacramento Peak Observatory in Sunspot, New Mexico.

Among planets, only Mercury and Venus can go in transit across the face of the Sun, as seen from the Earth, since they are the only planets whose orbits are inside that of Earth's. Pasachoff and Schneider have already used the 1999 transit of Mercury to unravel a centuries-old mystery known as the black-drop effect. (Their analysis was published in the journal Icarus and in the proceedings of an International Astronomical Union symposium on the transit of Venus.) This blurring of the distinction between a planet's silhouette and the edge of the Sun prevented accurate knowledge of the size of the solar system for hundreds of years. It had been seen at the very rare transits of Venus, which occur in pairs separated by over a century, and often falsely attributed to Venus's atmosphere. Pasachoff and Schneider, on the other hand, by observing and explaining a black-drop effect at a transit of Mercury observed from NASA's TRACE spacecraft, showed that no atmosphere was necessary, since Mercury's atmosphere is negligible and the spacecraft was outside Earth's atmosphere.

Transits of Mercury occur a dozen times a century, most recently in 2003. The next won't occur until 2016. Pasachoff and Schneider, in Hawaii are working with University of Hawaii scientists Jeff Kuhn, Don Mickey, and Garry Nitta to observe Mercury's stately progress silhouetted against the Sun for approximately five hours, from 9 a.m. to just after 2 p.m. local time (2 p.m. to sunset Eastern Standard Time).

Pasachoff, Schneider, and their University of Hawaii Institute for Astronomy colleagues used the Imaging Vector Magnetograph instrument on the telescope in the Mees Solar Observatory in a spectral-scanning mode to measure the sodium component of Mercury's extremely tenuous "atmosphere," measure its height, and determine how it varies from Mercury's pole to its equator. They also used the polarimetry capability of the instrument to try to detect the weak Mercurian magnetic field against that of the Sun.

Pasachoff and Schneider extended their interest in transits to the 2004 transit of Venus, the first to be visible from Earth since 1882. They teamed up with Richard Willson of Columbia University, whose NASA satellite ACRIMSAT is able to measure the total amount of energy from the Sun that reaches Earth. They were able to measure a decrease of a tenth of one percent in the radiation from the Sun because of Venus's blocking the Sun's disk. (They reported their results in the April 10, 2006, issue of the Astrophysical Journal.) The event provides a close analogy in our solar system for transits increasingly found for planets around other stars. NASA's Kepler spacecraft, to be launched in 2008, should discover hundreds of planets around other stars with this transit technique.

Williams College scientist Bryce Babcock will work with Kevin Reardon of Italy's Arcetri Observatory (Reardon is a Williams College alumnus) at the Sacramento Peak Observatory in Sunspot, New Mexico, part of the U.S. National Solar Observatory. From their 9200-foot altitude, they will use the transit of Mercury observed at the Dunn Solar Telescope there to measure the true sizes of the smallest features visible in the solar atmosphere. The availability of Mercury's sequentially blocking small features on the Sun from its position outside the Earth's atmosphere will make such observations possible. They will use camera systems obtained with a grant from NASA for Pasachoff and Babcock's studies of Pluto and other solar-system objects.

Reardon and Babcock will use a special instrument known as IBIS, constructed at the Institute in Florence and installed at the Dunn Solar Telescope, to construct a detailed map of the sodium atmosphere of Mercury. Andrew Potter, currently a visitor at the National Optical Astronomy Observatories, leads this experiment. The team in New Mexico, as well as Pasachoff and Schneider's team and Kuhn's team in Hawaii, will try to detect the spectrum of sodium in Mercury's atmosphere as it passes in front of the Sun.

Pasachoff and Schneider are working with scientists at Lockheed Martin Solar and Astrophysics Laboratory and at the Harvard-Smithsonian Center for Astrophysics, especially Leon Golub and Edward Deluca at the latter, to use not only NASA's 8-year-old Transition Region and Coronal Explorer (TRACE) spacecraft, which they had used previously, but also the new Hinode spacecraft, launched by the Japanese space agency on September 22, 2006, carrying telescopes from their Lockheed Martin and Harvard-Smithsonian collaborators.

Pasachoff's research about planetary transits is supported by a grant from the Committee on Research and Exploration of the National Geographic Society. He will be joined on Maui by Williams undergraduate Suranjit Tilakawardane, a student from Sri Lanka who is a senior astronomy major.

From the ground, the transit of Mercury will not be as visible as 2004's transit of Venus, since Mercury's disk will be too small to be seen without use of a telescope or binoculars. But the Sun is so bright that your eyes can be hurt if you look t it without special solar filters. So only people with access to solar filters or specially filtered telescopes, or who project the solar image on to a wall without looking through the telescope, will be able to see the November 8 event. The whole transit for beginning to end will be visible in Hawaii and in the extreme western United States. From New Mexico eastward to the Atlantic, the sun will set with Mercury's disk still silhouetted against it.

Related Sites:

Pasachoff Website on transits of Venus and Mercury: http://www.trasitofvenus.info

NASA site from Fred Espenak with a visibility map and table: http://sunearth.gsfc.nasa.gov/eclipse/OH/trasitO6.html


Story Source:

The above story is based on materials provided by Williams College. Note: Materials may be edited for content and length.


Cite This Page:

Williams College. "Rare Transit Of Mercury." ScienceDaily. ScienceDaily, 6 November 2006. <www.sciencedaily.com/releases/2006/11/061104090501.htm>.
Williams College. (2006, November 6). Rare Transit Of Mercury. ScienceDaily. Retrieved April 24, 2014 from www.sciencedaily.com/releases/2006/11/061104090501.htm
Williams College. "Rare Transit Of Mercury." ScienceDaily. www.sciencedaily.com/releases/2006/11/061104090501.htm (accessed April 24, 2014).

Share This



More Space & Time News

Thursday, April 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Nuclear-Level Asteroids Might Be More Common Than We Realize

Nuclear-Level Asteroids Might Be More Common Than We Realize

Newsy (Apr. 23, 2014) The B612 Foundation says asteroids strike Earth much more often than previously thought, and are hoping to build an early warning system. Video provided by Newsy
Powered by NewsLook.com
NASA Chief Outlines Plan for Human Mission to Mars

NASA Chief Outlines Plan for Human Mission to Mars

AFP (Apr. 22, 2014) NASA administrator Charles Bolden, speaking at the 'Human to Mars Summit' in Washington, says that learning more about the Red Planet can help answer the 'fundamental question' of 'life beyond Earth'. Duration: 00:48 Video provided by AFP
Powered by NewsLook.com
Nasa Gives You An Excuse to Post a Selfie on Earth Day

Nasa Gives You An Excuse to Post a Selfie on Earth Day

TheStreet (Apr. 22, 2014) NASA is inviting all social media users to take a selfie of themselves alongside nature and to post it to Twitter, Facebook, Flickr, Instagram, or Google Plus with the hashtag #globalselfie. NASA's goal is to crowd-source a collection of snapshots of the earth, ground-up, that will be used to create one "unique mosaic of the Blue Marble." This image will be available to all in May. Since this is probably one of the few times posting a selfie to Twitter won't be embarrassing, we suggest you give it a go for a good cause. Video provided by TheStreet
Powered by NewsLook.com
SpaceX's Dragon Spacecraft Captured by International Space Station

SpaceX's Dragon Spacecraft Captured by International Space Station

Reuters - US Online Video (Apr. 20, 2014) SpaceX's unmanned Dragon spacecraft makes a scheduled Easter Sunday rendezvous with the International Space Station. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins