Printer Friendly

Action at Jupiter.

Jupiter rises during mid-evening in October, and it's high enough for good telescopic views by midnight, shining in the east between Aldebaran and Beta Tauri. It's highest in the south by 4 a.m. daylight-saving time at the start of October and 2 a.m. at month's end--the best time for observing how the appearances of it two main belts have reversed since last year (see the photo and caption on the preceding page).

Even the smallest telescope shows Jupiter's four big Galilean moons with ease. Binoculars usually reveal at least two or three if you can brace the binoculars steady enough. Identify the moons with the diagram at left. You can see their precise positions at any time using skypub.com/jupsats.

All of the moons' interactions with Jupiter's disk and shadow in October are listed on the facing page. The moons are often tricky to spot when they pass in front of Jupiter; their shadows on the planet's disk are much easier to see.

Here are the times, in Universal Time, when Jupiter's Great Red Spot should cross the planet's central meridian, the imaginary line down the center of Jupiter from pole to pole. The dates (also in UT) are in bold. Eastern Daylight Time is UT minus 4 hours; Pacific Daylight Time is UT minus 7 hours. The Red Spot appears closer to Jupiter's central meridian than to the limb for 50 minutes before and after these times:

October 1, 4:39, 14:35; 2, 0:30, 10:26, 20:22; 3, 6:17, 16:13; 4, 2:09, 12:04, 22:00; 5, 7:55, 17:51; 6, 3:47, 13:42, 23:38; 7, 9:34, 19:29; 8, 5:25, 15:21; 9, 1:16, 11:12, 21:07; 10, 7:03, 16:59; 11, 2:54, 12:50, 22:45; 12, 8:41, 18:37; 13, 4:32, 14:28; 14, 0:24, 10:19, 20:15; 15, 6:10, 16:06; 16, 2:02, 11:57, 21:53; 17, 7:48, 17:44; 18, 3:40, 13:35, 23:31; 19, 9:26, 19:22; 20, 5:18, 15:13; 21, 1:09, 11:04, 21:00; 22, 6:56, 16:51; 23, 2:47, 12:42, 22:38; 24, 8:34, 18:29; 25, 4:25, 14:20; 26, 0:16, 10:12, 20:07; 27, 6:03, 15:58; 28, 1:54, 11:50, 21:45; 29, 7:41, 17:36; 30, 3:32, 13:28, 23:23; 31, 9:19, 19:14.

These times assume that the spot is centered at System II longitude 184[degrees]. If it has moved elsewhere, it will transit 1 2/3 minutes late for every 1[degrees] of longitude greater than 184[degrees], or 1 2/3 minutes early for every 1[degrees] less than 184[degrees]. The Red Spot has been gradually moving to higher longitudes for many years.

Markings on Jupiter appear a little more contrast through a blue or green eyepiece filter. The larger your scope, the darker the blue or green can be; you want enough light to see fine details clearly, but not so much that you lose visual details to glare (overexposure).

Try several magnifications to find the one that shows the most detail given the quality of the atmospheric seeing.

And keep looking! More and more flickers of features come out with protracted scrutiny.

RELATED ARTICLE: Minima of Algol

Algol, the prototype eclipsing variable star, fades every 2.87 days from its usual 2.1 magnitude to 3.4. It stays near minimum light for two hours, and takes several more hours to fade and to rebrighten. Shown above are magnitudes of comparison stars with decimal points omitted. (These geocentric predictions are from the heliocentric elements Min. = JD 2452253.559 + 2.867362E, where E is any integer. Courtesy Gerry Samolyk, AAVSO.)

Minima of Algol

Sept.   UT    Oct.    UT

2      17:48   1     9:55

5      14:36   4     6:43

8      11:25   7     3:32

11      8:14  10     0:21

14      5:02  12    21:10

17      1:51  15    17:58

19     22:40  18    14:47

22     19:28  21    11:36

25     16:17  24     8:25

28     13:06  27     5:14

              30     2:03
COPYRIGHT 2012 All rights reserved. This copyrighted material is duplicated by arrangement with Gale and may not be redistributed in any form without written permission from Sky & Telescope Media, LLC.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2012 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Celestial Calendar
Publication:Sky & Telescope
Geographic Code:1USA
Date:Oct 1, 2012
Words:715
Previous Article:Ceres & Vesta near Jupiter.
Next Article:Three asteroid occultations.
Topics:

Terms of use | Privacy policy | Copyright © 2020 Farlex, Inc. | Feedback | For webmasters