Classifieds:   |   |   |  Posted 11/28/2005 4:29 PM     Updated
11/28/2005 5:27 PM E-Mail Newsletters  A slow boat to Pluto,
Ants with hundreds of tiny eyes Q: How long does it take for
sunlight to reach Pluto? (Samantha, Mudgee, New South Wales,
Australia)  A. A beam of light blasts off the Sun at midnight,
Earth time (00:00:00 Coordinated Universal Time, UTC) and soars
outward. Passing each planet in turn, it zips by Earth in about
8 minutes at 00:08:19 UTC and hurtles on at 186 thousand miles
per second (300,000 km/s) for another 320 minutes until it
reaches cold and distant Pluto. About 5:30 in the morning
(05:28:06 UTC), it arrives.  That's an average travel time.
Pluto's distance from the Sun averages about 39 times the
distance of Earth from the Sun (a distance unit that is called
an Astronomical Unit, or AU).  Pluto's orbit — unlike any of our
other planets — is far from circular. So Pluto's distance from
the Sun varies from about 30 AU to almost 50 AU. Consequently,
the sunbeam's travel time to Pluto