Four months after it was first identified on June 4, 2002, the
distant planet Quaoar was announced to the world on Oct 7th. It
was what the news media terms a "one-day wonder", that is a story
worthy of mention for a day and then forgotten.
But not so for sky watchers. Quaoar is big news. In fact, at 800
miles in diameter (1250 km) it's the biggest discovery in the solar
system since Pluto was discovered in 1930.
And it's a neighbour of Pluto's as well. Both dwell in what
astronomers call the Kuiper Belt, which is a band of solar system
outback beyond the orbit of Neptune. The Kuiper Belt is similar to
the asteroid belt, but beyond Neptune and contains maybe 100 times
more material. So far 600 known Kuiper Belt Objects have been
identified, but most are only about 100 km (60 miles) in diameter.
This remote area of the solar system is still only partly mapped and
explored, which is why since 1992 astronomers have been aiming
an arsenal of high-tech telescopes in hopes of finding "something
big". It's the astronomical equivalent of panning for gold.
At any rate Chad Trujillo, an astronomer at Caltech using a
small telescope (the 48-inch Oschin reflector at Mount Palomar in
Southern California, shown right) and some very sophisticated
software, got lucky after seven months of looking and found
his nugget of gold, his "something big" out there.
Now professional astronomers are likely going to quarrel and
quibble that at 800 miles in diameter Quaoar isn't quite big enough to be
called a planet, but we astrologers don't lose sleep over pettiness
such as that. Heavens, we went ga-ga over Chiron in 1977 and it's barely
100 miles in diameter.
But just so you have some context, Quaoar's size, 800 miles is
approximately the distance between the following cities here on planet Earth:
New York and Chicago, Rome and Amsterdam, London and
Madrid, Toronto and Kenora, Vancouver and Saskatoon, Melbourne
and Brisbane, Cape Town and Durban. Get the idea? Quaoar isn't
small by any stretch.
Quaoar is not only big, it's massive. It contains more mass than
all the asteroids (located between Mars and Jupiter) put together,
although at this early stage astronomers aren't quite sure what makes
up the mass in Quaoar. Likely it's rock and various kinds of ice, but
somebody's going to get a PhD in astrophysics figuring this one out
definitively.
For the most part the orbit of Quaoar is outside the orbit of
Pluto, although not entirely. Pluto, with a 248-year long "year", has
a distinctly elliptical (egg-shaped) orbit which is mainly inside, but
occasionally outside Quaoar's almost perfectly circular 285-year
orbit.
There's even an image of Quaoar from the Hubble space telescope
(left). It's a bit indistinct because Kuiper Belt planetary bodies are not
your neighbours down the street. They are far quite away. Quaoar is
about 42 AU from the Sun. AU is shorthand for "astronomical
unit", the distance between Earth and the Sun, which means Quaoar
is 42 times further away from the Sun than Earth is. In other words,
Quaoar is about 6.3 billion km (4 billion miles) from the Sun.
That's far enough that it took the light about 5 hours to travel
from Quaoar to the Hubble telescope orbiting Earth for the above
photograph, and light travels at about 186,000 miles per second.
And hikers take note: this is not your weekend walk. One
calculation estimated it would take about 100,000 years of walking
to arrive at Quaoar. (My running shoes aren't that well built.)
Now for you trivia buffs, here's a dandy little tidbit to add to
your collection of interesting astronomical factoids. After Quaoar was
discovered, comparisons with older photographs revealed Quaoar had been
captured on film in 1982 by Charles Kowal, the astronomer who
discovered Chiron in 1977, but Kowal missed identifying Quaoar.
That's an oops. For an astronomer, this is considered embarrassing.
But those older photographs allowed astronomers to pin down
an exact orbit for Quaoar much sooner than is normally the case.
This is important for astrologers, too, because that pins down an
accurate ephemeris which is as crucial to
our work as it is for astronomers.
BTW, Quaoar's discoverer, Chad Trujillo, probably jumped the gun a
bit in naming this planet right away, as there is a stuffy bureaucratic
procedure amongst astronomers for anointing a new planet or
asteroid with a name. Technically the process has not got to naming
names just yet (October, 2002) and Quaoar is still known by astronomers as
2002LM60 (talk about prosaic!). Nonetheless, academic experts
well-acquainted with the arcane naming rituals of astronomers assure us
that Quaoar will likely survive this obscure scientific process anyway
inasmuch as planetary discoverers are allowed to name the objects they
find.
So what did discoverer Chad do after he had his 15 minutes of fame from finding Quaoar? Why, go look for some more planetary buddies in Quaoar's neighbourhood in the Kuiper Belt, of course. He said at the time that he thought there would be several more big ones out there, five or ten at least, a couple of which he said might be bigger than Quaoar or even Pluto.
Turns out he was right. Trujillo and the other astronomers on his team went on to discover Orcus, Sedna, and the as yet unnamed UB313. Click a link below to check out one of those new planets.
