Page 18 - Astronomy - October 2017 USA

OBSERVINGBASICS

B Y G L E N N CHA P L E Oct 1 N h
16 16 _

Track an Sept 1 g

asteroid pair E d 31 `

Path of Iris
e a
Pallas and Iris come within reach of small telescopes
these October nights. ARIES Nov 15
f
ver the years, I’ve star-hopping with my telescope
taken attendees to the appropriate location, 30
at public star and looking for a “star” in the 1°
parties on tele- position where the asteroid is
Oscopic voyages supposed to be. I make a sketch The brightest asteroid this autumn is 7th-magnitude Iris, which conveniently lies near
to all corners of the universe. that plots my suspect and the the brightest stars in Aries. ASTRONOMY: ROEN KELLY
We’ve viewed the Sun during surrounding stars, being sure
daytime (with an over-the- to include those near where the evening of August 13, 1847. 79 million miles away, and thus
front filter or by solar projec- asteroid’s path will take it on This was Hind’s first asteroid it peaks at magnitude 6.9.
tion, of course) and explored subsequent evenings. find; over the next seven years, If you’ve never seen an
virtually everything the night If a follow-up observation he would add nine more. Hind asteroid, this is one you’ll
sky has to offer, except for one confirms that my suspect is no is perhaps better known for want to check out. Not only is
class of objects: asteroids. longer there and a new “star” discovering the striking red- it bright enough to be picked
Most observers can recog- appears where I saw none ear- hued carbon star R Leporis, up through binoculars, but it
nize the Sun and the Moon, lier, I carve another notch in also known as Hind’s Crimson also spends autumn close to
planets and comets, and deep- my telescope tube. Well, actu- Star, and Hind’s Variable the three bright stars that form
sky objects from double stars ally, I record the asteroid Nebula (NGC 1555), which the the head of Aries the Ram. To
to nebulae, clusters, and galax- name and date of sighting in star T Tauri illuminates. capture Iris and put a notch in
ies at first glance. But an aster- a logbook. Through my little Like most asteroids, Iris your telescope tube (or, prefer-
oid? As the name implies 3-inch Edmund Scientific orbits the Sun in the gap ably, a note in your logbook),
— aster is the Latin word for reflector, I’ve seen more than between Mars and Jupiter. use the process I described
“star” — it looks like a star, so earlier. If you’re successful,
it doesn’t stand out when real go ahead and try your luck
stars clutter the same field. Through my little 3-inch reflector, with October’s other bright
Things would get more inter- I’ve seen more than 100 asteroids. asteroid, Pallas. It’s a bit more
esting if the viewer were to than a magnitude fainter than
return the next night and Iris and drifts across a rather
notice that one of the “stars” barren region near the border
had moved. But star parties 100 asteroids. If I’d notched the Studies of its brightness indi- between Eridanus and Fornax,
typically are one-night deals, tube each time I captured one, cate that this 130-mile-wide but you can do it.
so asteroids aren’t on the menu. I’d have whittled the poor asteroid rotates once every 7.1 Although asteroids might not
Before I continue, let me thing down to nothing! hours. Astronomers classify it be high on the list of showpiece
explain why I use asteroid as an S-type, or silicaceous. celestial sights, asteroid hunting
rather than the broader astro- All eyes on Iris Most of these stony asteroids is a fun and relaxing way to test
nomical term minor planet. This month, two of the first inhabit the inner part of the your observing skills.
Simply put, I like “asteroid” 10 asteroids discovered — asteroid belt. Questions, comments, or
better. Maybe it’s the negative 2 Pallas and 7 Iris — will be Iris reaches opposition and suggestions? Email me at
connotation of “minor planet.” within reach of small tele- peak visibility October 29, gchaple@hotmail.com. Next
Asteroids aren’t minor at all. scopes and even binoculars. when it lies about 2° south of month: touring Andromeda
Just ask the dinosaurs. Because I gear this column to the 2nd-magnitude star Hamal the Princess with a small tele-
Asteroids may not be jaw- the novice, let’s set our sights (Alpha [α] Arietis). At a typical scope. Clear skies!
dropping telescopic sights, on Iris, which is brighter and opposition, Iris glows at 8th or
but it’s fun to track their conveniently located near some 9th magnitude, but this time Glenn Chaple has been an
motion over several evenings. bright guide stars. around, opposition occurs avid observer since a friend
I enjoy taking out a finder English astronomer John when the asteroid is about as showed him Saturn through a
chart for a particular asteroid, Hind discovered Iris on the close to Earth as it can get, just small backyard scope in 1963.
BROWSE THE “OBSERVING BASICS” ARCHIVE AT www.Astronomy.com/Chaple.

18 ASTRONOMY • OCTOBER 2017