Couldn't find element LayerAd

Error finding content

Mercury Transit on May 7, 2003 - Windows to the Universe

Shop Windows to the Universe

Check out the fun Earth science related bumper stickers in our online store! Express yourself!
The dark disk of Mercury seen against the backdrop of the Sun during the transit. The transit is almost over, and Mercury appears near the edge of the Sun. This picture was taken with the Swedish 1 meter Solar Telescope (SST) of the Royal Swedish Academy of Sciences. The telescope is located at La Palma in the Canary Islands.
Click on image for full size
Image courtesy of The Royal Swedish Academy of Sciences.

Mercury Transit on May 7, 2003
News story originally written on July 2, 2003

The planet Mercury appeared to cross in front of the disk of the Sun on May 7, 2003. Astronomers call the event a transit. A transit is similar to a solar eclipse. However, a transit occurs when a planet, instead of Earth's Moon, passes between the Sun and Earth. Because planets are so much further away than the Moon, the planet does not completely cover the Sun during a transit like the Moon does during most eclipses.

This transit is the first of only 14 transits of Mercury during the 21st century. On average, transits of Mercury occur about once every seven years. The most recent previous transit of Mercury was on November 15, 1999; the next will be on November 8, 2006.

Only two planets, Mercury and Venus, ever transit the Sun as viewed from Earth. All of the other planets orbit the Sun further from Earth, and thus never pass between Earth and the Sun. Since the orbits of the planets are tilted, transits occur only some of the times when Mercury or Venus pass between Earth and the Sun. Usually the planets pass above or below the Sun as viewed from Earth, instead of directly crossing in front of the Sun.

Transits of Venus are much rarer than transits of Mercury. Venus transits happen only twice per century. We're in luck though - the next transit of Venus is coming along pretty soon on June 8, 2004!

Astronomers in the 1700's used transits of Venus to make the first accurate measurements of the distance between Earth and the Sun. By noting the precise time of the transit as viewed from different locations on Earth and by using their knowledge of the way planets orbit, astronomers were able to calculate the distance to the Sun. Sir Edmund Halley, of comet fame, was the first astronomer to realize that transits could be used to make that calculation.

Last modified July 2, 2003 by Randy Russell.

Shop Windows to the Universe Science Store!

Our online store includes books on science education, classroom activities in The Earth Scientist, mineral and fossil specimens, and educational games!

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Transits of Venus

The planet Venus periodically passes directly between Earth and the Sun. This event, which is somewhat similar to a solar eclipse, is called a transit of Venus. Viewed from Earth, Venus and Mercury are...more

Transit

A "transit" is the name of a type of astronomical event. A transit is similar to a solar eclipse, except a transit involves a planet, instead of the Moon, passing in front of the Sun. As viewed from Earth,...more

Mercury Transit on November 8, 2006

The planet Mercury will cross in front of the disk of the Sun on Wednesday, November 8, 2006. Astronomers call the event a transit. A transit is similar to a solar eclipse. However, a transit occurs when...more

Images & Multimedia

Here you will find links to all sorts of pictures, animations, videos, sounds, and interactive multimedia that are on Windows to the Universe Explore collections of images in the Image Galleries. Watch...more

More and more Moons of Jupiter

Astronomers have discovered a dozen new moons of Jupiter so far in 2003. Scott Sheppard and David Jewitt of the University of Hawaii and Jan Kleyna of Cambridge University led the team of astronomers who...more

Mars Opposition in August 2003

On August 27, 2003, Earth and Mars will be closer together than they have been in thousands of years. The centers of the two planets will be 55,758,006 kilometers (34,646,418 miles) apart at 9:51 Universal...more

More Moons around Jupiter & Saturn

Astronomers have recently discovered several more moons in our Solar System. Scott Sheppard and David Jewitt of the University of Hawaii and Jan Kleyna of Cambridge University announced the discovery of...more

Mercury Transit on May 7, 2003

The planet Mercury appeared to cross in front of the disk of the Sun on May 7, 2003. Astronomers call the event a transit. A transit is similar to a solar eclipse. However, a transit occurs when a planet,...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF