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May Brings Astronomical Bonanza
May Brings Astronomical Bonanza
2 May 2003
(Source: Sky & Telescope)

Sky & Telescope
Cambridge, Massachusetts

Alan MacRobert, Senior Editor
617-864-7360 x151

Roger W. Sinnott, Senior Editor
617-864-7360 x146

April 29, 2003

May Brings an Astronomical Bonanza

Keep your eyes on the heavens throughout this coming month. Astronomically speaking, May is bustin' out all over! Those in the know -- and in the right place at the right time -- will be treated to a lunar eclipse, a solar eclipse, the passage of the planet Mercury in front of the Sun, and the nationwide celebration of Astronomy Day.

Transit of Mercury

The excitement begins on Wednesday, May 7th, when the Sun, the innermost planet Mercury, and the Earth will form a straight line in space. For five hours Mercury will crawl across the solar disk, appearing as a slowly moving black dot. Skywatchers throughout most of Europe, Africa, and Asia can see the entire event unfold. Those living in Japan, Alaska, parts of Australia, and the northeastern parts of North and South America will see part of the transit after sunrise or before sunset.

This is the first of 14 transits of Mercury to take place in the 21st century, and the first since November 1999. Mercury's next transit across the solar disk favors observers in Pacific Rim countries and will take place in 2006 on November 8th.

To watch the transit you must observe the Sun, which is very dangerous unless proper precautions are taken. Never look directly at the Sun, with or without optical aid, unless you have a safe solar filter and understand its instructions for use. Tips for observing the transit safely -- either indirectly by projection or directly through properly filtered optics -- appear below. We also provide tables listing the times to watch from various cities worldwide []. If your city isn't listed, use the times given for the location nearest you.

Astronomy Day 2003

Saturday, May 10th, is Astronomy Day. This annual event, now celebrating its 30th anniversary, began as a high-profile way of drawing public attention to the science and the hobby through exhibits and activities at urban centers. It has since mushroomed in size and scope. Hundreds of astronomy clubs, observatories, museums, colleges, and planetariums worldwide now host family-oriented Astronomy Day events and festivities to show how enjoyable and exciting astronomy can be. For more information, see our online article "Astronomy Day: Bringing Astronomy to the People", To find a club or other astronomy-related organization near you, search's directory,

Since 1989 Sky & Telescope has given its prestigious Astronomy Day Award to the events or displays judged most successful in achieving the core concept of the event: "Bringing Astronomy to the People." [] The grand prizewinner receives a plaque awarded at the Astronomical League's annual convention and a $250 gift certificate from Sky Publishing, good toward the purchase of magazine subscriptions, books, star atlases, software, photographic prints, globes, or other products.

The Astronomical League maintains a Web page listing Astronomy Day events across the USA,

Lunar Eclipse

On Thursday night, May 15-16, the full Moon will pass directly through the northern part of the Earth's shadow, providing a colorful spectacle for skywatchers throughout the Americas, Europe, and Africa. For North Americans the 3 ?-hour event happens in "prime time," from about 10 p.m. to 1:15 a.m. Eastern Daylight Time (7 p.m. to 10:15 p.m. Pacific Daylight Time, though the early partial phases occur before sunset/moonrise on the West Coast).

In early May Sky & Telescope will issue a more detailed press release about this eclipse, including a timetable and instructions on what to look for. Note that this is the first total lunar eclipse in 2 ? years and the first one visible across the Americas since January 2000. This year brings two total eclipses of the Moon, and the second, on November 9th, will also be visible from the United States.

Solar Eclipse

At the end of the month, on Saturday morning, May 31st, the Moon will pass directly between the Earth and the Sun. The last time this happened, on December 4, 2002, skygazers in Africa and Australia witnessed a total solar eclipse. But this time the Moon will be a little farther from the Earth, and the Earth a little closer to the Sun, so the Moon's angular size won't be quite large enough to mask the Sun totally. Instead, skywatchers in Iceland, northern Scotland, and parts of Greenland will experience a brilliant ring of sunlight -- the hallmark of an annular eclipse. Elsewhere across Europe, as well as for parts of Asia and North America, the Moon will glance across the Sun, taking no more than a "bite" out of its disk when viewed through a safe solar filter. See our accompanying timetable for details:

Solar Safety

When viewing the Sun, regardless of the time of day, simple, proper precautions are required. For the May 31st solar eclipse, it is easy to view the event indoors by pinhole projection. Use a pin to poke a tiny hole in an index card. Hold the card up to the Sun in a window, and display the image of the Sun projected by the pinhole onto a solid white background (for example, a sheet of paper). You'll be able to watch the Sun go through all phases of the eclipse. To see tiny Mercury move across the Sun on May 7th, you'll need a larger, sharper image, which you can get by projection through a small telescope or binoculars.

For those who prefer direct views, safe solar filters for telescopic or naked-eye observing are available from a variety of suppliers []. Other safe ways to observe the Sun are described in a series of articles in the Observing section of

More information about all these events, and how to enjoy them, appears in the May 2003 issue of Sky & Telescope magazine.

Note to Editors/Producers: Sky & Telescope is making the following illustrations available to the news media, Permission is granted for one-time, nonexclusive use in print and broadcast media, as long as appropriate credits (as noted in each caption) are included. Web publication must include a link to

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Last Updated: 2 May 2003