Dolores Beasley

Headquarters, Washington, DC

(Phone: 202/358-1753)

Susan Hendrix

Goddard Space Flight Center, Greenbelt, MD

(Phone: 301/286-7745)

RELEASE: 00-76

Exclusive images from the Solar and Heliospheric Observatory
(SOHO) spacecraft will show four planets marching together on the
side of the sun opposite from Earth, near the climax of a line-up
of planets that is fascinating amateur astronomers around the
world this month. On May 15, Mercury, Venus, Jupiter and Saturn
will all be in the field of view of the Large Angle and
Spectrometric Coronagraph (LASCO) instrument on SOHO.

Skywatchers can view the show on the Internet at the sites
referenced at the end of this release; presently, Saturn, Jupiter,
and Mercury can be seen with SOHO. NASA TV will broadcast video of
the planetary parade Friday, May 5, and updated versions will be
broadcast Friday, May 12, and Monday, May 15.

Because the planets travel around the sun at different
speeds, their position in the sky as seen from Earth changes.
Rarely, some or all of the planets appear together in the same
area of sky, a circumstance called planetary conjunction. In the
past, people attributed special significance to celestial events,
so such alignments have altered the course of history. The current
conjunction presents a striking but benign spectacle, with
Mercury, Venus, Mars, Jupiter and Saturn grouped most tightly on
May 17.

As the planets neared the sun’s direction in recent weeks,
observers on the ground were frustrated by the glare of sunlight
preventing them from seeing the planets. But what was hard for
other skywatchers was ideal for SOHO. Using masks to blot out
direct rays from the solar surface, the LASCO coronagraph watches
for gaseous outbursts from the sun’s atmosphere. It also sees
stars beyond the sun and has discovered many unknown comets.

The widest field of view spans 15 degrees across the sky,
which is just enough to accommodate the four planets on May 15.
Venus will be heading into the picture while Mercury will be on
its way out. Mars will be out of view on the left, being almost
twice as far across the sky as Mercury. Jupiter and Saturn will be
closer to the solar direction but the sun will already be leaving
them behind.

The sun’s direction in the sky, relative to the stars, keeps
shifting to the left as the Earth and SOHO orbit around it. The
appearance of the planets and the sun in roughly the same
direction means that the Earth too is temporarily in line with the
other planets, although on the opposite side of the sun.

The planets keep altering their relative positions because
they orbit around the sun at different rates. Changes in their
locations, especially of the massive Jupiter and Saturn, alter the
position of the center of mass of the Solar System, so that sun
itself wobbles. Such wobbles seen in other stars have enabled
astronomers to detect alien planets.

SOHO is a project of international cooperation between the
European Space Agency and NASA. The LASCO coronagraph was built
and is operated by a multinational team led by the US Naval
Research Laboratory.

Images are available on the Internet at:


The NASA Video File normally airs at noon, 3:00 p.m., 6:00
p.m., 9:00 p.m. and midnight Eastern Time. NASA Television is
available on GE-2, transponder 9C at 85 degrees West longitude,
with vertical polarization. Frequency is on 3880.0 megahertz, with
audio on 6.8 megahertz.