May 16, 2000
--If someone could turn off the Sun for a while on Wednesday,
star gazers would be treated to a remarkable sight. The two brightest
planets, Venus and Jupiter, will pass less than 0.01 degrees
apart at 1030 UT on May 17. Unfortunately, the close encounter
will take place just 7 degrees from the bright Sun, making it
impossible to see with the naked eye."If Jupiter and Venus were farther from the Sun
on May 17, the conjunction would be a real eye-catcher,"
says astronomer Dr. George Lebo, a 2000 Summer Faculty Fellow
at the Marshall Space Flight Center. "The human eye can
distinguish objects separated by angles greater than 50 arcseconds,
but Venus and Jupiter will only be 42 arcseconds apart. At closest
approach the pair would appear to merge into a single brilliant
Nevertheless, you can still monitor the encounter thanks to the
ESA/NASA Solar and Heliospheric Observatory (SOHO).
SOHO has an advantage over most stargazers. Coronagraphs on the
satellite can block out the Sun's bright light in order to see
nearby stars and planets as well as the Sun's faint corona. The
conjunction will be easy to see in images from SOHO's wide field
coronagraph that are posted on the SOHO
realtime images web page.
Above: On May 15, 2000, SOHO's
wide field coronagraph recorded this image of the Sun surrounded
by Mercury, Venus, Jupiter and Saturn. A well-known asterism
is also visible in the upper left of the image. The blue disk
blocks out the Sun's bright light; the white circle near the
center shows the true size of the Sun. At 1030 UT on May 17,
Venus and Jupiter will be less than 0.01 degrees apart.
This close conjunction has already been compared to the 2 B.C.
conjunction of the same planets that is often identified as the
Star" reported in the book of Matthew.
Star of Bethlehem: An Astronomical and Historical Perspective,"
Susan S. Carroll writes:
On June 17, 2 BC, Venus and Jupiter joined .... in the
constellation Leo. The two planets were at best 6 (arcseconds)
apart; some calculations indicate that they actually overlapped
each other. This conjunction occurred during the evening and
would have appeared as one very bright star. Even if they were
6 apart, it would have required the sharpest of eyes to
split the two, because of their brightness.
Venus-Jupiter conjunctions like the one on May 17, 2000,
are not terribly rare, notes John Mosley of the Griffith Observatory
in an essay on Planetary
Alignments in 2000. According to Mosley, the last time Venus
and Jupiter were closer than on May 17, 2000 (separated by less
than 42 arcseconds) was at 3:47 on July 21, 1859, when their
centers were 32 arcseconds apart (there was no partial occultation).
The next time will be at 12:45 on November 22, 2065, when their
centers will be 16 arcseconds apart and the northern edge of
Venus passes in front of Jupiter.
The Conjunction at a Glance
- Jupiter and Venus will pass
42 arcseconds apart at 10:30 UT on May 17.
- Both planets will be full phase
with apparent polar diameters of 9.8 and 30.8 arcseconds.
- At closest approach their limbs
will be separated by only 22 arcseconds.
- The Venus-Jupiter conjunction
takes place 7 degrees from the Sun.
- The last time Jupiter and Venus
were so close was in 1859; the next time will be in 2065.
Although Venus and Jupiter will appear to be very close together
on May 17, there's no danger of a collision. The two are really
very far apart. Venus will be 257 million km from Earth, while
Jupiter will be 896 million km away. The two are separated from
each other by a comfortable 639 million km.
Watch the Venus-Jupiter conjunction at
the SOHO Realtime Images page!
As Venus passes by Jupiter on May 17 the
five classical planets (Mercury, Venus, Mars, Jupiter and Saturn)
will span just 19° 25'. The cluster is too near the sun for
naked-eye observations, but it's perfect for SOHO coronagraphs,
which will be able to see all of the planets except Mars.
Above: This computer animation shows the relative positions
of Jupiter and Venus as seen from Earth on May 17, 2000. The
six-frame sequence begins at 0830 UT and ends at 1330 UT. The
minimum separation between the two planets occurs near 1030 UT.
Also shown are the Galilean satellites Io, Europa, Ganymede,
and Callisto. The horizontal field of view is approximately 15
arcminutes (the angular separation between Callisto and Jupiter
is approximately 7').
SOHO is a cooperative project between the European Space
Agency (ESA) and NASA. The spacecraft was built in Europe for
ESA and equipped with instruments by teams of scientists in Europe
and the USA.