Chapter 10:

Mercury

Links from Chapter

SEDS (Students for the Exploration and Development of Space) Homepage on Mercury
USGS Web Site with Images of Mercury
MESSENGER Mission
Upcoming Transits of Mercury

Transits
Transit of Mercury, 15 November 1999
TRACE Observations of the 15 November 1999 Mercury Transit
Schneider, Pasachoff, Golub paper about the 1999 transit
Transit of Mercury Movie

BepiColumbo's Lander Axed

February 22, 2004
For financial reasons, the European Space Agency has eliminated BepiColumbo's lander. The mission will then contain two orbiters.

Transit of Mercury across the Sun Widely Viewed from Space and from the Ground

Mercury passes between the Earth and Sun only a dozen times a century. The May 7, 2003, transit was imaged with NASA's Transition Region and Coronal Explorer (TRACE) spacecraft, with the Solar and Heliospheric Observatory (SOHO), and from many professional and amateur ground-based sites.

This transit is a warmup for the June 8, 2004, transit of Venus. It will be the first transit of Venus since 1882. Images of that transit of Venus appear in the text. See http://www.williams.edu/astronomy/eclipse/transitVenus.htm
See also http://www.transitofvenus.org.

May 7, 2003, transit of Mercury:

A TRACE combination image, composited from over 5 hours of observations in an extreme ultraviolet-wavelength:
http://vestige.lmsal.com/TRACE/POD/images/Mercury2003_combo.gif

A TRACE movie in an extreme-ultraviolet wavelength:
http://vestige.lmsal.com/TRACE/POD/movies/Mercury2003_cpk.avi

A TRACE movie in white light, with vignetting limiting the view to a small region of the Sun by defining a circular lower edge to the field of view:
http://chippewa.nascom.nasa.gov/TRACE/mercury_2003/mercury2003_WL_small2.mov

A ground-based image by Philippe Jacquot of Annecy, France
http://astrosurf.com/studiosaros/Transit.html

A movie from the Global Oscillation Network Group (GONG):
http://www.gong.noao.edu/cgi-bin/generic_js_movie.pl

A composite image from the Udaipur, India, GONG site, carefully co-registered so that the overall Sun stayed steady. The solar rotation blurred out the sunspots:
http://gong.nso.edu/mercury_transit03/images/UDcomposit.jpg

A ground-based composite white-light image by D. Dierick:
http://users.pandora.be/create/mercury.htm

A Solar Mini-Eclipse on May 7, 2003
Planet Mercury Passes in Front of the Solar Disk

European Southern Observatory Press Release May 3, 2003

European Southern Observatory

A solar mini-eclipse! On May 7, 2003, Mercury, the innermost planet in the solar system, willpass in front of the Sun and produce a solar eclipse. But this event will hardly be noticed. Mercury's small disk will indeed barely be bigger than the point of a pencil. Even the smallest sunspots on the solar surface are as big as the Earth and measure 10,000 km or more in diameter, while Mercury's equatorial diameter is only 4878 km.

Bathed in intense sunlight, this small, hot planet moves around the Sun in an elliptical orbit at a mean distance of only 58 million km, much closer to the Sun than other inner planet, Venus (108 million km) and the Earth (150 million km).

The disk of Mercury is very small and will be very difficult to see. A powerful telescope is needed to observe this event and to show clearly how Mercury moves across the solar disk. The disk of Mercury is indeed only 13 arcseconds across (while the solar disk measures about 1800 arcseconds). This corresponds to the size of a 1 EURO coin located at the top of the Eiffel Tower as seen from the ground. Therefore, Mercury will only block 1/20,000th of the Sun's light.

Mercury Transits

Passages of Mercury in front of the Sun, or "Mercury Transits" in astronomical terminology, are comparatively rare events, due to the different orbital inclinations of the Earth and Mercury as they move around the Sun.

In order for a Mercury transit to happen, the planet must be located directly between the Earth and the Sun and also near one of the two points in its orbit where Mercury's orbital plane intersects that of the Earth. We then face the dark side of Mercury - the hemisphere that is not illuminated by the Sun - and see it as a small dark spot moving across the bright solar disk.

There are about 13 Mercury transits each century and they follow in time intervals of approximately 13, 7, 10 and 3 years. The most recent one took place in November 1999 and the next will be on May 7, 2003 and November 8, 2006.

The next Mercury transit happens on May 7. It lasts from about 7:13 hrs CEST (Central European Summer Time) until 12:32 hrs CEST (5:13 to 10:32 UT) and the contour of the small planet as it moves across the solar disk can be seen from all places where the Sun is above the horizon and the sky is clear. The best observing conditions are from Europe, Africa and Asia.

Observations of the transit

Note, however, that this event cannot be observed with the unaided eye - - this would also be extremely dangerous because the enormous brightness of the Sun will cause total blindness in a fraction of a second!

Observations can only be made by means of telescopes which project the solar image onto a white screen.

Public observatories, planetaria and other educational institutions will arrange special events on this occasion. News about such arrangements will appear in the local press.

Live images on the web

On this special occasion and in order to provide for everybody the chance to watch this event, the European Southern Observatory (ESO) and the European Association for Astronomy Education (EAAE), together with the Institut de Mecanique Celeste et de Calcul des Ephemerides (IMCCE) and the Observatoire de Paris in France, are providing live images and a running commentary for all interested parties. It is also planned to display images obtained at observatories in the Belgium, the Czech Republic, Hungary, Italy and Spain, and possibly others. The availability will depend on the weather situation in the various places.

Full information and many weblinks to other educational sites are available via the special website at:
http://www.eso.org/outreach/eduoff/vt-2004/mt-2003/mt-intro.html
On this site, extensive background information about Mercury and the Sun can be found and, in particular, useful sheets for school students and teachers in many languages. Live images from professional telescopes (depending on the weather at the observing sites) will be available on the special webpage:
http://www.eso.org/outreach/eduoff/vt-2004/mt-2003/mt-display.html
and it will also be possible to ask questions in "real-time" to astronomers via this page.

Venus Transit on June 8, 2004

The Mercury Transit of May 7 is also a kind of "general rehearsal" to the even rarer Venus Transit event on June 8, 2004. The last such event took place in 1884, so that no living person has ever seen one. The above mentioned organisations are also preparing for a major public event on that occasion. Provisional information is already available at the VT-2004 website.

Transit of Mercury on May 7

The early morning of Wednesday, May 7, 2003, will see a transit of Mercury. The only part of the United States from which the transit will be visible is the northeast. In Boston, the transit will end at 6:34 a.m., about an hour after sunrise, with the sun only 10 degrees above the eastern horizon.

The entire transit of Mercury will be visible in Europe. Many people are especially interested in this transit of Mercury, the first since 1999, as a precursor to the June 8, 2004, transit of Venus, which will be the first transit of Venus since 1882.

Mercury transit images

The Mercury transit on 7 May 2003 will be partly visible from La Palma. We plan to observe it with the Swedish 1-meter Solar Telescope from close to sunrise until last contact.

Weather, seeing, and computer networks permitting, we will display quasi real time images (updated every few minutes) at http://www.solarphysics.kva.se/Mercurytransit7May2003. Later the same day, we will make a movie available at the same site.

European Space Agency release for the transit of Mercury
Sky and Telescope article on the transit of Mercury
Williams College site for the transit of Venus

MESSENGER Mission to Mercury Starts Being Built

Johns Hopkins University APL Press Release, March 29, 2002

The first mission to orbit the planet Mercury took a big step toward its scheduled March 2004 launch when NASA's MESSENGER project received approval to start building its spacecraft and scientific instruments.

MESSENGER - which stands for MErcury Surface, Space ENvironment, GEochemistry, and Ranging - passed a thorough four-day critical design review last week, during which a project advisory panel and NASA assessment team examined every detail of the mission and spacecraft design.

"The review was very successful," says Max R. Peterson, MESSENGER project manager at the Johns Hopkins University Applied Physics Laboratory (APL), Laurel, Md. "Both panels confirmed that our designs are sound and meet the mission's science and engineering requirements. We're ready to move to the next stage."

MESSENGER team members are building flight hardware now and will begin integrating parts on the spacecraft this November, Peterson says. After launch and a five-year journey through the inner solar system, MESSENGER will orbit Mercury for one Earth year, providing the first images of the entire planet and collecting information on the composition and structure of Mercury's crust, its geologic history, the nature of its thin atmosphere and active magnetosphere, and the makeup of its core and polar materials. While cruising to Mercury the spacecraft will fly past the planet twice - in 2007 and 2008 - snapping pictures and gathering data critical to planning the orbit study that begins in April 2009.

A key MESSENGER design element deals with the intense heat at Mercury. The sun is up to 11 times brighter than we see on Earth and surface temperatures can reach 450 degrees Celsius (about 840 degrees Fahrenheit), but MESSENGER's instruments will operate at room temperature behind a sunshield made of heat-resistant Nextel fabric. The spacecraft will also pass only briefly over the hottest parts of the surface, limiting exposure to reflected heat.

"The project is well on its way," says Dr. Sean C. Solomon, MESSENGER principal investigator from the Carnegie Institution of Washington (D.C). "Exploring the many mysteries of Mercury will help us to understand all of the terrestrial planets, including Earth. The team is eagerly looking forward to assembling and launching the spacecraft and to the first new data from the innermost planet."

In July 1999, NASA selected MESSENGER as the seventh mission in its innovative Discovery Program of lower-cost, highly focused space science investigations. APL manages the $286 million project for NASA's Office of Space Science and will build and operate the MESSENGER spacecraft.

MESSENGER Mission Web Site: http://messenger.jhuapl.edu NASA Discovery Program Web Site: http://discovery.nasa.gov

Mercury Images

Mark Robinson has some reprocessed images of Mercury available on his web site .