Electronic reference resources cover a wide range of materials. Databases and bibliographies are some of the most familiar, along with online encyclopedias and guides. There are even materials that are available for handheld devices, such as iPads or smart phones. Some of the resources listed may only be available through a subscription service. If one of the subscription resources looks interesting to you, check with your local library to see if they have access to it. For more information about using electronic resources, take a look at Using This Site.
Online Atlases
The Full Moon Atlas: Lunar NavigatorInternational Luna Society "The Official Website of the Moon"
(c) 1999-2010
This excellent online atlas breaks down the different regions of the lunar surface and identifies over 2,500 craters, mountains, lakes, seas and valleys. The map is interactive, allowing you to click a region to zoom in and see a detailed image of the geographic features, and is broken into images for the Earth-side and far-side of the moon. This atlas will help you learn the names of the features you see on the lunar surface when viewing through your telescope or binoculars.
Google Mars
Powered by Google and NASA
Google teamed up with NASA scientists to create a detailed map of the Mars surface, identifying geographical features, landing sites, and even news stories (with links to the articles). The map can be viewed as a color-coded elevation map, a visible map that shows what you would see from orbit, or an infrared map showing temperature variations. Also, with the downloadable Mars in Google Earth, you can even view the map in 3D.
Skymaps
Kim Thalassoudis
Each month, this site offers a two-page guide to the night sky, including a sky map, monthly calendar, and a list of objects to view with your binoculars, telescope, or just using your eyes. The best part: These monthly guides are completely free for personal, non-commercial use and you are welcome to redistribute the handouts educational use.
Your Sky Tonight Star Charts
Seeing in the Dark & PBS
PBS has created an interactive sky chart that allows you to enter your time and location, choose the labels you want, and then print out a customized star chart to take outside with you while you explore the skies. The site also provides links to other resources and topics and a photo gallery.
Handheld Device Atlases
Star Walk: Interactive Astronomy GuideVito Technology Inc.
This handy application tracks the stars above you in real time as well as the satellites that are passing overhead. You can also change the time, so that you can see what the sky will look like tonight, next month, or even ten years ago. Switch the application over to night mode to take it outside with you and have it point out exactly which objects you wish to see. Compatible with iPad, iPod Touch, or iPhone. (Estimated download cost: $4.99)
Star Chart
Feel Great Publishing Limited
Point your iPhone or iPad (with built-in compass) at the sky and Star Chart will tell you exactly what you are looking at. Or, if your device doesn't have a compass, you can scroll the screen with your fingers. It also allows you to search for specific objects and helps you locate them in the night sky. (Estimated download cost: $2.99)
Pocket Stars Astronomy Software for Pocket PC, Smart phone, and Desktop
Nomad Electronics
This program comes in three versions and is designed to work with your Windows-enabled device. It includes an adjustable star chart and astronomy reference terms. The smart phone version also allows you to change the program's language to one of seven different choices. (Estimated download cost: $20)
Almanacs, Dictionaries and Encyclopedias
AccessScience: The Online Encyclopedia of Science and TechnologyMcGraw-Hill
Clicking "Astronomy and Space Science" on the homepage will take you to a list of topics that you can explore with a variety of explanations. You will only be able to see excerpts without an account, so check with your local library to see if they have a subscription.
The Astronomical Almanac Online
U.S. Nautical Almanac Office/Her Majesty's Nautical Almanac Office
This site, also available in a print format, provides tables to help locate the sun, planets, and moon at various times during the year. Some of the information is only available in print, while some is specifically designed for the web.
Astronomy for Kids: Astronomy DictionaryKidsKnowIt Network
This simple dictionary breaks down the complicated astronomy terms into definitions that kids can understand. The rest of the site helps children understand outer space and the objects they might see.
Cosmos: The SAO Encyclopedia of Astronomy
Swinburne Astronomy Online
This free online encyclopedia allows you to search for your topic or browse by starting letter. Each entry provides a simple explanation with illustrations when appropriate, and links to other, related entries.
Online Astronomy Dictionary
Web Finance Inc
This is a free online dictionary for astronomy terms. It highlights essential terms on the homepage with links to the entries, and you can search or browse through the database of over 2,000 terms to find a clear definition for the term you are looking for.
Free Databases
FactMonster: Astronomy and Space ExplorationFamily Education Network
This database, geared towards younger users, has a variety of articles about different space-related topics that the amateur astronomer may find interesting. The search function will enable users to find information on topics or words that they come across while researching. Also, the atlas portion of this database has a calculator that will help you determine your latitude and longitude, which is often needed to determine viewing times.
Subscription Databases
Science In Context: Browse Topics, Physics and AstronomyGale, Cengage Learning
This database contains a variety of articles, ranging from explanations and definitions to journal and news articles. Clicking on a topic will bring up an explanation of the topic, along with links to related entries and articles from news, magazine, and academic sources. A variety of multimedia resources are available along the right-hand side of the page, as well.
Opposing Viewpoints: Space Exploration
Gale, Cengage Learning
Many amateur astronomers are interested in the much larger realm of space exploration in addition to their personal, observational exploration. This database provides information on some of the largest debates about space exploration along with articles to back up both sides of each debate.
