Date: 1999 - 2000
When is a comet's tail in front of the comet instead of
When the comet is receeding from the sun (going away), the tail is in front
of the nucleus. The solar wind acting on the nucleus is sending material
away from the sun, and much faster than the comet is moving.
The phrase "in front of" that you use is a bit misleading. It is more
correct to say that the tail of the comet will always face away from the
sun. The tail of the comet is the result of energy from the sun reaching
the comet and either melting water ice or sublimating sold carbon dioxide
(dry ice) along with the subsequent release of organic molecules which had
been held in the structure. Since the enregy from the sun emantes from the
sun to other universal bodies, the tail which results from the impact of
that energy will also travel away from the sun. Note that as the comet
approaches the sun (flying in its direction, but not directly at it) the
comet's tail will face back, approximately opposite the direction of travel.
The more the comet's direction is not directly towards the sun, the greater
the deviation from directly behind the comet the tail will be. After passing
the sun, assuming there is still more of the comet left to continue
traveling, the tail will continue to face away from the sun, towards the
outer part of our solar system.
To try to depict this graphically:
with the large O representing the sun, and the small
o representing the comet. Note the tail faces away from the sun
note, in this case, the comet is not headed directly
towards the sun, but the comet's tail again faces away from the sun
Note, as the comet passes the sun, the tail continues
to point away from the sun
The comet has now passed the sun, and the tail
still faces away from the sun
Please note, in each of the above depictions, the direction of comet travel
is right to left, and I am a bit limited in the document with the ability to
align exactly what would be seen.
Thanks for using NEWTON!
Richard R. Rupnik
Internal Quality Auditor
A comet's tail points away from the Sun, because it is blown that direction
by ions streaming out from the Sun. So, whenever a comet is moving away
from the Sun, its tail will stream ahead of it.
Richard Barrans Jr., Ph.D.
When the comet comes near the Sun, it gets hot. Some of the comet
is ice and frozen gases. This stuff melts in the heat of the Sun, and
makes a cloud around the comet head. The heat from the Sun makes the
cloud boil off in the direction away from the Sun. So, the tail
always points away from the Sun. If the comet is coming towards the
Sun, then the tail points "behind" the comet. If the comet is going
away from the Sun, the tail points "in front of" the comet. If the
comet is going past the Sun, the tail points "on the side" of the
Dr. C. Grayce
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Update: June 2012