Resource of the Week: Sky and Telescope Interactive Observing Tools
By Shirl Kennedy, Senior Editor

While hard core astronomy geeks may already be aware of this site, it was new to us and we figured that a lot of you may not have seen it yet. Since most of us are at least somewhat interested in “what’s up there,” we thought we’d let you know about some of the cool stuff available on the Sky and Telescope magazine website. If you click the “more info” button to the right of the sun- and moonrise data, the window expands to provide “detailed information about the Sun, Moon, and five naked-eye planets.” Clicking “less info” returns it to the original, smaller size.

The centerpiece, if you will, of this collection of javascript-powered astronomy apps is SkyandTelescope.com’s Almanac.

SkyandTelescope.com’s almanac presents basic astronomical data customized for your location, for any date from A.D. 1600 to 2400. The information available for display includes sunrise and sunset times, morning and evening twilight times, moonrise and moonset times, the Moon’s phase, a list of naked-eye planets visible in the evening and morning skies, rise and set times for each of these objects, and more.

The page provides detailed instructions for using this tool, including how to preset your geographic location. You may have to turn off your popup blocker because the almanac launches in a separate window, which is about a quarter of the size of a full window. (Note that you may also need to fiddle with text size or screen resolution to be able to see everything in the almanac window.) The almanac displays:

• a graphic representation of the Moon’s phase and then reports the Moon’s age (in days since the last new Moon)
• the Julian Day number (for “official” astronomical timekeeping)
• your location (country and nearest large city)
• the current date and time (in Universal Time, which is essentially the same as Greenwich Mean Time)
• your latitude and longitude, time zone, local date and time, and whether daylight-saving time is in effect

Note that the daylight saving time box may or may not be checked; you’ll need to do it manually if it’s not correct.)

A row of buttons underneath this information allows you to go backward or forward in time — by a week, a day or an hour. Below the buttons, you’ll see small text boxes showing when the sun and moon rise and set, and when twilight begins and ends. Directly below are boxes showing which planets are visible in the evening and morning. The large text area at the bottom — you might have to scroll to see everything — includes information about “any significant astronomical events that occur on the specified date, such as a meteor shower or a conjunction of the Moon and a bright planet or star.”

If you want to change the date or time, type the new info into the boxes at the top and click the “calc” button to update the display. Click “reset” to return the data for the current date and time.

Among the other tools here, we especially liked The Phase of the Moon, a utility that shows and tells the moon phase for any date, AD or BC. And there are a variety of other applications that astronomy buffs will enjoy:
+ The Minima of Algol (”The star Algol (β Persei) was the first eclipsing variable star ever discovered, and it’s still the most famous one.”)
+ Transit Times of Jupiter’s Great Red Spot (”Now you can calculate the dates and times (local and Universal Times) when the center of the Great Red Spot should cross Jupiter’s central meridian….”)
+ Chasing the Moons of Jupiter (”With help from our interactive JavaScript utility, you can always tell which of Jupiter’s four largest satellites is which.”)
+ Chasing the Moons of Jupiter
+ Seeking Saturn’s Moons (”With help from our interactive JavaScript utility, you can always tell which of Saturn’s brightest moons is which.”)
+ The Elusive Moons of Uranus (”Our handy JavaScript utility can help users of moderate to large telescopes find as many as five Uranus’s brightest satellites.”)
+ Mars: Which Side Is Visible? (”To compare what you see on Mars with a map, you need to know which side of the planet you’re looking at. Our handy Mars Profiler tells you that….”
+ The Martian Moons in 2007 and 2008 (”If you’ve never spied Mars’s two satellites, Phobos and Deimos, the end of the year is the best chance you’ll ever get.”)

As long as you’re on the magazine’s website, don’t leave without trying the Interactive Sky Chart, which allows you to build “a custom naked-eye map of the whole sky for any place on Earth, at any time of day or night, on any date from 1600 to 2400.” And there’s even a Mobile Sky Chart (hello, Gary); alas, it’s for Verizon subscribers only.