Looks Like I’ll be Saying Ophiuchus Sunday

Here’s a Google Trends graph showing searches for “Ophiuchus” over the last 30 days. The spike comes after a Minnesota astronomy instructor, Parke Kunkle, mentioned in an interview that the sun glides through the constellations of the zodiac on a different schedule than it did a few thousand years ago, and therefore the dates for the zodiacal signs used in astrology no longer match up with the sun’s position. To add to the fun, he mentioned that, in addition to the famous twelve, the sun also passes through Ophiuchus, the serpent bearer. Chaos ensued.

As Kunkle knew, the shift he spoke of has been known for over 2,000 years. It is due to the Precession of the Equinoxes, the same wobble that means Polaris has not always been and will not always be our North Star. Precession is covered in most Astronomy 101 courses, including ours. Why this old news went viral would be an interesting question to explore some time.

Astrologers were quick to point out that they use a “Tropical Zodiac” anyway. In it the signs are merely seasonal markers, now independent of the constellations from which they originally drew their names. Not that I endorse the practice of astrology, but fair enough. As someone interested in sundials, I have seen the zodiacal signs used as seasonal markers in just this way.

Case closed? Hardly! It’s a great excuse to demonstrate the Precession of the Equinoxes and point out Ophiuchus at the 2011 New Year show this Sunday and Monday. (See the calendar on the planetarium site for more info.)

December Skyshow and Spring Schedule

I haven’t posted here this fall, so perhaps an early New Year’s resolution is in order.

Today and tomorrow we present our final shows of the fall semester. We’ll be featuring some research news from the Gettysburg College Observatory as we’ll as a total lunar eclipse viewable from our region in the early AM hours of Dec 21. It’s the last favorable for eastern North America until 2015, so let’s hope it’s clear!

The Spring 2011 schedule is set and available at the planetarium (paper) and on the web site. In addition to the monthly skyshows, we’ll be doing the New Year show again, and in April something new: a solar system scale model made by taking a 1,000-yard walk.

Clear Skies!

Venus – Mercury Conjunction


Venus and Mercury will appear together in the evening sky in late March and early April. Look very low in the west about 20 minutes after sunset. It’s a difficult sight, for which you’ll need clear skies and an unobstructed western horizon. Mercury is a greatest elongation on April 8 and will rapidly descend toward the sunset afterward. Venus, by contrast, will be setting later and later over the next few months. Image created by Stellarium. Local horizon panorama shows the Gettysburg College Observatory outdoor platform.

Clouds Move in on Leonids

Some unpredicted (at least according to the forecast I read) clouds moved in in the early AM of the 17th, interfering with local views of the shower. Some people reported seeing a few meteors earlier in the evening. Further summary at the December skyshow. If you have a Leonid story to share, send me an e-mail.

Looking good for the Leonids

Should be clear tonight. Read the following message forwarded by Larry Marschall, if you are still looking for more info:

LEONID METEOR SHOWER TO PERFORM LATE TONIGHT

The annual Leonid meteor shower should be reaching its climax late
tonight in the U.S., from about 1 a.m. your local time to dawn Tuesday
morning November 17th. “Viewing conditions will be excellent, because
the Moon won’t be lighting the sky this year,” says Alan MacRobert,
senior editor of Sky & Telescope magazine. “You might see 20 or 30
meteors per hour under ideal dark-sky conditions.”

Most people, unfortunately, don’t have a dark, natural night sky
anymore. “But even if there’s light pollution in your sky, the
brightest meteors will shine through,” says MacRobert. “Just find a
dark spot with a wide open view overhead and no glary lights nearby.”

Another point in our favor: Sky & Telescope predicts that the most
reliable part of the annual shower will reach its peak when North
America is having its prime meteor-watching hours from midnight to
dawn.

A second, more intense outburst of Leonids may happen about 12 hours
later, during the early-morning hours of November 18th in Asia.
There’s only an off chance that some activity from that later burst
will still be going on by the time the Earth turns halfway around and
the Leonids again become visible from the Americas on the morning of
the 18th.

Wherever you are, no Leonids will be visible before the shower’s
radiant point (in Leo) rises around local midnight. The “radiant” is
the perspective point from which all the meteors would appear to
originate if you could see them coming from the far distance. In
reality, you see them for only the last second or two of their lives
as they plunge into the top of Earth’s atmosphere and burn up in
white-hot streaks.

Be sure to bundle up warmly; meteor-watching is always colder than you
expect. The ideal equipment is just a comfortable lounge chair, a warm
sleeping bag, and a pillow. Just lie back, watch the stars, and be
patient. The best direction to watch is wherever your sky is darkest,
probably straight up.

Notice the meteors’ flight paths. Only those streaking away from the
direction to the constellation Leo, in the eastern sky, are Leonids.

Another, less-known meteor shower is going on simultaneously: the
Taurids. They’re sparse but tend to be very bright. If you see a slow,
bright meteor heading away from the direction to Taurus, that’s a
Taurid.

“And you’re bound to see a few ‘sporadic’ meteors that aren’t
associated with any major shower,” says Sky & Telescope editor in
chief Robert Naeye.

For more about meteor-watching, check out SkyandTelescope.com, the
website of Sky & Telescope magazine.

# # #

Setting the Planets


We began work this morning on calibrating the moon and planets on our 1966 Spitz A3P. They are controlled by the analogs (little mechanical models) seen here. Each analog models the motion of the earth, sun, and its respective planet. That motion is transferred to the diagonal mirror that reflects a dot for that planet onto the planetarium dome.