Astronomy Online

Useful Web Addresses

This is the area where you may find useful Web addresses, connected to Astronomy and Astrophysics and related fields of science. They can then be accessed by means of the installed links.

The addresses are listed according to area and type, but there will be overlaps. Note also that many of these addresses lead you to Web-sites with extensive lists of further connections and links. Thus, by starting from the present page, you will be able to access a major part of all Web sites in the world that are related to the natural sciences.

In order to avoid loosing yourself in this 'jungle', it is recommended that you move slowly and reflect upon what you are doing, before you press the button to proceed. It will also be an advantage to consult the Astronomy On-Line Search Guidelines before you start. In any case, you should try to use the built-in search engines, wherever they are available.

Note that you may always add the addresses of particularly interesting sites to your bookmarks. This will then make it easier for you to access these sites again in the future.

List of Addresses

You will find below important gateways to useful Web addresses, with a short explanation at each one. Some of the addresses are active, so you may click on them to reach the indicated sites. These addresses have been selected to give you an impression of the great diversity of the information which is available on the Web.

1. Online Astronomical and Other Resources (

This is the main gateway from ESO to other `Astronomical Sites' on the Web. From here you will be able to reach the Homepages of many observatories and institutions. There is also a Search Engine which will help you to get faster to the goal of your enquiry.

Note in particular the three sites at the Strasbourg Data Center: StarWorlds with astronomical and related organisations; StarBits with abbreviations, acronyms and symbols; and Star Heads from where you may access the Homepages of individual astronomers.

Finally, this page also gives access to two important research papers, dealing with astronomical information of the Web. They may be somewhat technical in scope, but they contain a wealth of information about individual astronomical Websites, classified by type.

2. Very Large Telescope (

Very comprehensive information about the ESO Very Large Telescope, now being built at Cerro Paranal in Chile. With many drawings and photos.

3. Sky Calendar Tool (

This site will allow you to calculate an astronomical calendar for several observing sites, including La Silla, where a telescope will be available for Astronomy On-Line Participants.

4. Weather Maps (

How will the weather be? Here you will find satellite photos showing almost all of the Earth at any given time. This page is maintained by the Institut für Meteorologie der Freien Universität Berlin. You may also find it useful to check the weather forecast at your national meteorological institute, or via the CNN Weather Service with individual forecasts for all major cities in the world.

5. Life on Mars?

A subject of much recent interest to the astronomical world is the question of whether or not signs on ancient life have been found in a meteorite from Mars that was picked up some years ago in Antarctica. Much has been written in the press and experts have divided opinions about this exciting topic.

If you would like to have the opportunity to judge yourself, we suggest that you consult first the original article in the Science journal (August 1996) that started off the debate. Here you will find, in scientific language, but generally comprehensible to high-school students, the various arguments in favour of a possible biological origin. Do they convince you?

Voices of caution were raised, soon after the appearance of that article. For instance, an article in Scientific American (October 1996) recalls that in 1961, it was also thought that evidence for life on Mars had been found. More research is obviously needed on other meteorites.

If you want to follow this discussion in the future, a good site with frequent updates is the Mars Page of the Federation of American Scientists. Here you will also find very complete information about the Viking Landers that visited Mars in the 1970's.

An extensive collection of documents and images about the known meteorites from Mars is available at the Mars Meteorite Home Page of the Jet Propulsion Laboratory (JPL).

6. Volcanic Activity

There are many volcanoes on the Earth's surface and several of them are active at any time. This activity comes in all sizes, from minor emissions of gas and dust, to giant eruptions during which many cubic kilometres of material are injected into the upper levels of the Earth's atmosphere.

Astronomical observations may suffer from such eruptions, because dust in the atmosphere absorps the light from the objects in the sky. Moreover, this absorption (in astronomical terminology: extinction) is not the same for all colours; normally, it is highest in the blue spectral region. The atmospheric dust therefore not only dims the light, it also makes stars and galaxies look more red than they really are.

It is thus possible to measure the content of dust in the atmosphere by observing the change of the colour of well-known astronomical objects. Exact colour measurements of standard stars serve this purpose. Another example is the colour of the Moon during a Lunar Eclipse; the bright red (rather than dark red) colour which was seen during the Total Lunar Eclipse on September 27 indicated that there was comparatively little dust in the atmosphere at that time.

You may check the current status of the Earth's volcanoes by visiting the Volcano World Webpage. Here, you will find the latest information about volcanic eruptions and many interesting links to volcano-related research.


Astronomy On-line | EAAE | ESO | Help | Search