||Last revised: 06/14/09
Pluto Challenge: Start Page
Welcome to the annual Pluto
Challenge: since the year 2000
this page has been helping amateur astronomers "discover" Pluto -- the
most neglected and controversial of (dwarf?) planets. Two "challenges"
are presented here. They are meant to encourage small-scope users to push the boundaries of technology and
achieve the goal of viewing
and/or imaging Pluto. All the advise, charts, and links, to help
you accomplish this task are here. During "Pluto season" -- from
yearly opposition to disappearance in the solar glare -- this page is updated -- so check back often. The Pluto
Challenge topic of the Message Board is a good place to post public
information and read a compilation of comments from other Pluto observers. You
can also e-mail suggestions, observations, and images.
Pluto and You
Have you seen Pluto lately? With the (dwarf?) planet at
opposition in June, late spring is a good time to start looking.
Most beginning amateur observers have trained their telescopes at the brighter, naked-eye
planets numerous times. Next-up, in
planet spotting difficulty, is discerning the disks of Uranus and Neptune,
through a telescopic star-hop. But, how many
amateurs out there have "done" all the (dwarf?) planets, by viewing disk-less
Pluto though their instruments? Isn't it time you added this target to your
"seen it" list?
Why not make it a habit to locate this (dwarf?) planet throughout the observing season? This page contains information for finding the
(dwarf?) planet with precise position coordinates, maps, and star-hops. See Charts
Pluto Small-Scope Viewing Challenge
Spots New Pluto Moons!
Amazing images of Pluto's newly discovered moons.
Planet Meets Triple Star (ESO 8.2-m telescope) Images from July 20,
Pluto (Peoria Astro Society)
General notes on verifying Pluto in the eyepiece.
Pluto (dwarf?) Planet Profile
Lists up-to-date facts about Pluto.
What we know and don't about Pluto and its moon Charon.
Clyde Tombaugh (1906 - 1997)
A site about Pluto and its discoverer, Clyde Tombaugh.
A ballad about Pluto's discovery and planetary status.
and Charon: Ice Worlds on the Ragged Edge of the Solar System. This
complete book covers the history or Pluto: from discovery, to the
realization of its true size, to the discovery of Charon, and current status
as "big man" in the Kuiper Belt.
Pluto. Pluto and its place in the Kuiper belt. This book is a history of
theories and actual discoveries concerning these objects. Discusses how the
science "is done" on those mountain-top observatories.
young readers, try this book from the Isaac Asimov's 21st Century
Library of the Universe series.
Much misinformation has
been heaped upon the preparatory Pluto observer. The limiting-magnitude "rule-of-thumb"
puts the 13.8-magnitude (dwarf?) planet right at the visual limit for 5"/127-mm
telescopes, and "common knowledge" says at least an 8"/203-mm scope
should be employed for
visual attempts. Yet, a search of the Internet turns up discouraging
advice for users of medium-sized amateur telescopes:
Pluto. Always ignore Pluto. You can't see it, even with the 10-inch
The University of St. Andrews Astronomical Society website's
"What You Can See Now" page for May 2001
requires at least a 12-inch diameter telescope and is very difficult to see,
even for advanced amateurs."
Astronomy Resource Site's "What’s Out Tonight?" page
I can only hope that the comments attributed to
the above websites are a reflection of the local observing conditions and not
meant as sage advice to observers world-wide.
On the other end of the debate are reports of Pluto sightings in
"impossibly" small instruments.
Some attribute this to the power of suggestion: your mind expects to see something in the target zone and
does. But, consider this quote from a letter entitled "Pluto in a
4-1/2-inch Scope," that appeared on page-14 of the August 2000 issue of Sky
& Telescope magazine:
really need is not a large telescope but a dark sky, some patience, and a little
experience with averted vision."
Scott Ewart of Philadelphia , PA.
Mr. Ewart took his 4.5" reflector to the
Texas Star party in 1999. He met Sky & Telescope contributing editor
Stephen James O'Meara, who described sighting Pluto with a 4" refractor in
Hawaii. O'Meara urged Ewart to search for Pluto in the little reflector:
"After about a half hour of effort, I could say for sure that yes, that's
not my imagination, that's it!"
search of Internet-based astronomical discussion groups reveals more Pluto
sightings, through even smaller instruments. Examine a compilation of such
reports in the Visual
Sightings Logbook. Counting O'Meara's Hawaiian observation, I've come
across two small-scope sightings by well-regarded, published
astronomical authors. I believe this is enough to explode the 8"-scope
"rule" for observing Pluto. After all, the dictionary tells us
that a rule-of-thumb is "a useful principle having wide application but not intended to be strictly accurate or reliable in every situation."
Unfortunately, the 8"-rule has become widely enshrined as an absolute in
astronomical circles. Even Mr. Ewart's letter in Sky & Telescope
begins by acknowledging the rule: "Too many times to recall, I've read or
heard that you need at least an 8- to 10-inch telescope to see Pluto."
#1: What is the smallest aperture telescope that
you can see Pluto in?
Help dismiss the myth: observe Pluto in a
sub-8" telescope and spread the word if you succeed. Start by reading
the small-telescope Visual
Sightings Logbook, to learn how others accomplished this feat. Post your
sighting on the Message
Board. Users of big scopes have an advantage: they
can spot the (dwarf?) planet and then employ aperture masks to determine the aperture
The Pluto Small-Scope Imaging Challenge
But even if you can't spot the (dwarf?) planet visually, that
shouldn't stop small-scope users from imaging the area. CCD or film-based
instruments can go to deeper magnitudes than the eye, to capture this little (big
#2: What is the smallest aperture telescope that
image Pluto in?
In the 7-decades since Clyde Tombaugh
imaged Pluto, on photographic plates through a large telescope, technology has
come a long way. Now, with the right equipment and preparation, the same
imaging feat is within the grasp of a back-yard amateur astronomer.
is the point of this Challenge? Many amateurs are looking for ways to use their equipment
to support "real" science, but feel their equipment is too small to provide
useful results. As amateur observers, our equipment choices often contend with
contradicting needs: good portability versus good aperture. So, based on some
"rules of thumb," we must
settle on a comprise imaging system that fits these parameters. As a result, one might be tempted to think: "Oh, I can drive the 30-miles to position myself for the asteroid
occultation, but the
portable scope I'd use probably won't be able to gather enough light to make
imaging worth it." Maybe it
I urge all telescope users to try imaging the (dwarf?) planet
apart. You can view some sample
images here. If you have two
(2) images showing Pluto's motion: send the images or URLs
here and I'll post or link to them on the Images
& Samples page of this challenge. Include details of how the images were made
(aperture, camera, image time, location, sky conditions, etc.). I'll post update messages on the
Imaging message area of the message board.
Big scope users, that know they can image the (dwarf?) planet
with ease, can try stopping down the telescope aperture with a
cardboard mask. See the FAQ for
details. How far down in aperture can you go and still capture the (dwarf?) planet?
Jocelyn Bell Burnell at the IAU meeting
makes a presentation to the august body on the August day that Pluto was
voted out of the planet club.
--IAU/Lars Holm Nielsen
Throughout the Pluto Season
Now you'll need to examine the view in the main
telescope to verify the (dwarf?) planet, with the aid of a detailed chart. As you
narrow down the (dwarf?) planet's location with these charts, switch to
higher-power eyepieces to limit the view and separate the faint (dwarf?) planet from the
Sky & Telescope publishes an article and map for locating the outer planets
every year. Stars to
14-mag are typically shown.
Astronomical Society of New Zealand has Pluto charts for southern
- The yearly Astronomical Calendar
Ottewell, usually has a photographic star chart marked with Pluto's locations over the
course of several years.
- If you need to examine the area in greater
detail, use a good photographic chart from an online atlas such as the STScI Digitized Sky Survey.
Don't wait-out the year to start
your observing! The (dwarf?) planet
will be setting soon after sunset in October and lost in the solar glare
Northern observers shouldn't put off observing
this (dwarf?) planet. For them, Pluto was highest in the sky in the year 1980! The
(dwarf?) planet has been heading toward the descending node of its solar orbit ever since
-- it will be lower
to the horizon each passing year. Also, the (dwarf?) planet's orbit will position
it against ever denser areas of the Milky Way. With more stars in the
field of view, "on the spot" detection will be harder, but detection at very-high
power by motion comparison will be easier.
06/14/2009 Challenge page updated for 2009.
07/15/2007 Challenge page updated for 2007.
06/11/2006 Challenge page updated for 2006.
07/08/2006 Pluto occultation and moon names update
07/24/2006 Added Douglas W. Neal image to "Reference" section of
08/12/2006 Added August to mid-October chart in "Charts".
08/24/2006 Added update on IAU vote on planetary status.
03/11/2007 Changed planet to (dwarf?) planet