Fwd: The planets line up -- but don't panic! Watch them with SOHO and answer our quiz!

[tony...@myinternetuk.com]

04 May 2000 16:13:43
sci.astro
From: ay...@nova.astro.utoronto.ca
Subject: The planets line up -- but don't panic! Watch them with SOHO
and answer our quiz!
To: sci.astro

ESA Science News
http://sci.esa.int

04 May 2000

The planets line up -- but don't panic! Watch them with SOHO and
answer
our quiz!

For followers of Nostradamus, this is a chance to relish. What better
time
than the year 2000 -- prelude to the new millennium -- to predict all
sorts
of catastrophes driven by celestial objects? And the planets, jointly
taunting the doomsayers, have chosen to dance together before their
eyes.
Mars, Jupiter and Saturn clustered for the first time on 6 April,
within a
circle 9 degrees wide. On 14 April, they gathered again in a 5-degree
circle.
And last month's dance was just a prelude to this month's fiesta. On 5
May,
Mercury, Venus, the Moon and the Sun join in too, grouping in a circle
of 26
degrees.

The Moon will soon part company, but the planets will continue to
cluster
till 17 May, when Mercury, Venus, Mars, Jupiter and Saturn, plus the
Sun,
will be crammed within a 19 deg 25 min circle. A crowded picture
indeed.
But even a doomsayer should know that such gatherings are not
uncommon.
In the last couple of thousand years, the Sun, the Moon, Mercury,
Venus,
Mars, Jupiter and Saturn have gathered within a 30-degree circle
twenty-eight times, and today is the twenty-ninth.

All this with no dangerous consequences for the Earth, for the simple
reason
that nothing can happen. The Solar System is so wide and empty that
the
planets are like grains of sand scattered in space. The Sun and Moon
induce
tides on Earth, for the entertainment of sunbathers and windsurfers on
the
beaches. The tides vary as time passes, in ways well explained by the
changing configuration of Sun and Moon.

Planets also cause tides on the Sun. In order of importance, Jupiter,
Mercury,
Venus and the Earth all exert tidal effects, which have not yet been
measured.

The present alignment of the planets is a special event for those
studying
this effect. It will delight the scientific researchers who are
interested in
the influences of the planets on the Sun and, conversely, the
influence of the
Sun on the planets, including the Earth.

But that's all. Earthquakes? Other calamities and disasters? Pure
fancy!

So what is this planetary grouping? When we look up at night,
everything
within our field of vision is projected onto the dome of the sky, the
celestial sphere. And if two or more objects lie in almost the same
direction, they will appear close together on the dome even if in
reality
they are they are at vastly different distances. A planetary grouping
is
therefore a perspective view of an alignment in space. Is that all?
Yes.

Watch the planets with SOHO

Last month was the only opportunity to see the planets gathering in
line,
with the naked eye. Now they are invisible because they are too close
to
the Sun in the sky. However, that is an advantage for the ESA-NASA
SOHO
spacecraft, which observes the sky in the Sun's vicinity with its
coronagraph LASCO. Already Jupiter, Saturn and Mercury are in the
field
of view, as seen in the accompanying SOHO image.

During the coming days the planets change positions relative to the
Sun, and
on 15 May Venus will join them in the LASCO field of view. But then
Mercury
will move out of the picture, so the unprecedented sight of four
planets near
the Sun will not last long. It will be shown in a mid-May report, here
on the
ESA Science web site.

Meanwhile, anyone can watch the dance of the planets near the Sun, day
by
day, by visiting the SOHO web page of "Very latest images" and looking
at
the LASCO C3 image,
http://sohowww.estec.esa.nl/data/realtime-images.html

So don't panic, but enjoy the cosmic spectacle and consider the
following
test of your astronomical skills!

Cassini-Huygens is in the line too

Jean-Pierre Lebreton, ESA's project scientist for Huygens says: "If
you had
good enough eyes (I mean a very big telescope) you would be able to
spot the
Cassini/Huygens spacecraft as well, in the alignment of the planets!"

The NASA-ESA Cassini/Huygens spacecraft is bound for Saturn, where
ESA's
Huygens probe will land on Saturn's largest moon, Titan. At present
Cassini/Huygens is on its way towards Jupiter, having exited the
Asteroid
Belt last month. Let's do a little exercise. Cassini/Huygens was
observed
from the Earth with a modest telescope a few days after launch in
October
1997, and also in August 1999 after the Earth flyby.

Now the questions to our faithful readers:

How big a telescope would be needed to see Cassini/Huygens in mid-
May
2000? And at what angle with respect to the Sun-Earth line would
you
see it?

Experts will judge your answers and the three best will win a small
model
of the Huygens probe. All participants will receive a Huygens brochure
and a
poster. The contest is not open to professional astronomers or space
scientists/engineers.

Send your answers -- not later than 15 June 2000 -- by email to ESA
Science
web or by normal mail to:

Monica Talevi
Science Programme Communications Service
P.O. BOX 199
2200 AG Noordwijk ZH
The Netherlands

USEFUL LINKS FOR THIS STORY

* Cassini/Huygens Earth Flyby
http://sci.esa.int/content/news/index.cfm?aid=12&cid=384&oid=12037
* SOHO hotshots
http://sohowww.estec.esa.nl/hotshots/
* Sky & Telescope report on tidal forces
http://www.skypub.com/news/special/may5_2000.html
* Early scientific results from the Cassini/Huygens Earth swingby
http://sci.esa.int/content/news/index.cfm?aid=12&cid=384&oid=12040
* Cassini mission status repoort 14-04-2000
http://www.jpl.nasa.gov/status/cas/cs000414.html

IMAGE CAPTION:
[http://sci.esa.int/content/image/index.cfm?
aid=1&cid=1&oid=18600&objecttypename=news&ooid=18595]
Three planets are almost in line with the Sun itself.

--
Andrew Yee
ay...@nova.astro.utoronto.ca

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