Finding North

I am constant as the northern star,
Of whose true-fix'd and resting quality
There is no fellow in the firmament.
- Julius Caesar (III, i, 60 – 62)

The stars at the front bowl of the Big Dipper, Merak and Dubhe, are called pointer stars. They point to Polaris, the North Star. Draw an imaginary line from Merak to Dubhe. Extend it five times the distance, and you'll end up at Polaris.


Contrary to Shakespeare, the North Star is neither constant nor fixed. Some facts about Polaris:

• It resides in the constellation Ursa Minor.
• It is the tip of the handle of the Little Dipper.
• At magnitude 2, it is only the 48th brightest star in the night sky.
• It is a variable star, its brightness varying over 4 days.
• It is a binary star or double star. The second star is a faint magnitude 9.
• It wasn't always the North Star. Thuban, in the constellation Draco, was the North Star around 3000 BC. In 3000 AD Gamma Cephei in the constellation Cepheus will become the North Star.
  

References:

Polaris
Wikipedia on the North Star
Wikipedia on Polaris
List of Brightest Stars
Constant as the North Star
Shakespeare Quote

How to Use a Planisphere

If you made your own planisphere but can't quite figure out how to use it, then this video is for you. The first four minutes of the video covers planispheres; the rest covers binoculars.

How to Find the Planets

The easiest way to locate all the planets is to follow Sky & Telescope's directions. Go to This Week's Sky at a Glance, and scroll down to This Week's Planet Roundup.

Mercury, Venus, Mars, Jupiter and Saturn are bright and easy to spot even from the city. Uranus and Neptune require a telescope and a finder chart. Pluto is still listed for old times' sake and is a challenge to find. You'll need a big scope, dark sky, and detailed star chart.

How to Identify Jupiter's Moons

If you have a telescope or binoculars that let you see Jupiter's moons, then the Jupiter's Moons JavaScript Utility from Sky & Telescope will help. It allows you to identify the four brightest moons at any given time. Adjust the time using your UT offset to determine the local time. The tool automatically retrieves the UT offset from your computer, but you may want to verify that it is correct.

You can confirm for yourself that the moons are constantly changing position. Click on one of the buttons repeatedly, e.g., "+1 hour," to simulate this.

How to Calculate Your Universal Time Offset

Universal Time, often abbreviated UT or UTC, is more or less the same as Greenwich Mean Time (GMT). Some astronomy tools require that you know the offset, or time difference, between UT and your time zone. The offset can also be used to convert UT to your local time.

You can look up your offset here:

Map-based lookup
Text-based lookup

If you're on Daylight Saving Time (DST), you may have to add one hour to the offset, depending on the tool. Note that if your offset is e.g., -8 hours, it becomes -7 hours with DST (not -9).