Planning a Viewing Night

If you are going to go out an view the night sky it is handy to have some idea of what is going to be visible. Apart from the obvious impact of weather and clouds on your chances of viewing you also need to consider several questions.

1. What phase is the Moon? If you want to observe the Moon you need to ensure it is up at night. If it is Full Moon it may be too bright to observe comfortably unless you have a moon filter for your eyepiece. If you wish to look at faint objects such as other galaxies and nebulae a bright Moon can interfere with your viewing.
2. Which planets are visible? The planets move relative to the background stars. Just because Mars is visible one February doesn't mean that you will be able to see it the following February.
3. Which constellations are visible? Different regions of the sky are visible in the evening sky at different times of the year. Orion is visible in the evening sky during summer for southern hemisphere observers whereas Scorpius rises much later and is best viewed during the winter months.
4. When does it get dark? Summer nights are generally warmer than winter ones but you have to wait longer for sunset.

You will also need to consider some other practical questions:

• Where will I be observing or viewing from? Ideally you want a site with a clear view of the sky, preferably flat and safe. Try and avoid any nearby lights.
• What equipment do I have or need? Be realistic in your planning. If you want to view faint galaxies you need a decent telescope. On the other hand you can spend an entire night without a telescope just gazing at the constellations, the Milky Way, meteors and even satellites with your unaided eyes. Binoculars are handy and allow you to see even more. They are great for viewing many star cluster. If possible print out a sky map or bring along a planisphere to help you locate stars and constellations. Cover your torch with red cellophane so that you don't lose your night vision when reading your sky map.
• What is the weather going to be? Check to see if a clear sky is likely or if rain is expected. If it is going to get cold ensure you have warm clothing with you.

This page provides you with some resources and places where you can find the answers to these questions. Our next page, What's up tonight? is a structured activity guiding you through this preparation. It will be available online shortly.

Online sources

• Astronomical Information from Geoscience Australia allows you to compute Sunrise/Sunset, twilight and Moonrise/Moonset times for any location. You can also determine lunar phase, and Sun and Moon azimuth and elevation plus browse planet data for major Australian cities.
• Bureau of Meteorology Weather Information. Click on your state map for local forecasts and warnings.
  The Radar Network page allows you to check radar images for some regions of Australia. This is handy for monitoring current rainfall and storms.
  The Satellite Images page provides visible and infra red images for the whole of Australia, handy for checking cloud cover. Both the radar and satellite sites allow you to view looped images that provide a mini-movie of recent trends.
• CalSky allows you to produce a customised celestial calendar for any location and date.
• Fist and Finger Rules has a useful set of diagrams showing the various angular measurements using hands. It also links to a useful introductory article by Sky & Telescope on nomenclature.
• Free Star Charts from SFA. A set of four charts for the whole sky is available for free download. You can also download useful student exercises.
• Heavens-Above.com allows you to produce customised skycharts, celestial calendars and satellite pass predictions for your location. The site is an excellent way to find out which satellites will pass overhead during a viewing session. It also predicts when Iridium flares will be visible.
• Skymaps.com provides free, monthly sky maps as PDF files that can be downloaded and printed out. Southern and northern hemisphere charts are available and contain details of what is visible and highlights for the month.
• Southern Skywatch is an excellent Australian site that provides detailed guide to what is up in the sky. It is updated monthly, sometimes more often if there is a specific event. It has numerous diagrams and screenshots from planetarium programs showing what you can see. Highly recommended.
• Tips for Holding a Viewing Night is a more detailed guide on this Outreach and Education site for teachers or those planning a public viewing night. It can also be downloaded as a 330 KB PDF file.
• After School Astronomy Clubs has a wealth of resources and ideas. You can also sign up for a discussion group to share your ideas and questions with others.

Software

• Planisphere is a free Windows-based program that you can download and use to produce a planisphere for your location.
• Stellarium is an excellent open-source planetarium/sky simulator program available for Windows, Mac OS X and Linux platforms.

Print Resources

• 2007 Australian Sky Guide, Dr N. Lomb, 2006, Powerhouse Publishing, ISBN 1 86317 120 7. This annual guide is a clear, concise guide is written by the Curator of Astronomy at Sydney Observatory, part of the Powerhouse Museum . Its compact size and useful information make it a handy reference.

An excellent resource for the science department or library.

• Astronomy 2007, Glenn Dawes, Peter Northfield, Ken Wallace, 2006, Quasar Publishing. This is an excellent and very detailed annual guide for observers. The depth of information is well presented, allowing observers at different levels of expertise to all find it useful. The publisher's website has useful suggestions on how to use the guide as well as lots of helpful information for beginners.
• WA Astronomy Almanac is produced annually by Perth Observatory. "It contains a wealth of background material, with sky maps to aid identification of planets, and presents a year's worth of astronomical events ranging from daily moonrise to the peak time of meteor showers in an easy to understand format and Western Australian Time."