This year the Mars opposition will occur on 7 November. Mars will be quite bright with a visual magnitude of -2.33 and will have a size of about 19.9 arcseconds. At opposition, it will be at coordinates (J2000) 02h50m, +15°52' in the constellation of Aries. It will appear as a bright read-orange object that should rise at about the same time the sun sets (and set at about the same time as the next sunrise). The season on Mars will be late winter in the northern hemisphere and late summer in the southern hemisphere; LS=321° for those familiar with that notation. At opposition, the entire visible disk of Mars is illuminated; it is in its full phase, much like a full moon. Before and after opposition, it will be in a gibbous phase; it can never have a crescent phase since Mars is further away from the Sun than Earth and thus can never be between Earth and the Sun.
Due to the relatively high ellipticity of Mars' orbit, the opposition date will not be the date of closest approch. The closest approach will occur on 30 October at which point Mars will be only about 43 million miles (about 69 million km) away. Since it is closer, it will be larger than at opposition with a size of 20.2 arcseconds. One would expect that closer and larger would imply brighter, but since it is not a full phase, it only has a visual magnitude of -2.26 (remember, astronomers are a backwards sort so smaller, or more negative, magnitudes are brighter).
For some more detailed information on the opposition, you can check out these links: a paper by Jeff Beish, on of the A.L.P.O. Mars Section assistant coordinators or a page by P. Clay Sherrod of the Arkansas Sky Observatory
Who are we?
The International MarsWatch is a group founded by amateur and professional astronomers more than 30 years ago to facilitate better communication between the amateur and professional Mars observing communities. This network currently consists of over 150 professional and amateur astronomers who are interested in Mars or active in Mars research.
What are we doing?
The primary purpose of this project is frequent CCD imaging of Mars using B,V,R or other standard filters and visual drawings and photos in order to monitor the planet's atmospheric dust and cloud activity. Our goal is to get a complete, global, image of Mars for every day of the opposition observing season.
Secondary goals include imaging or spectroscopic characterization of the surface color and mineralogy, characterization of the growth and retreat of the polar caps, and analysis of atmospheric water vapor content. Because Mars rotates at nearly the same rate as the Earth and it also has a dynamic atmosphere that exhibits hourly, daily, and seasonal changes, frequent observations from observatories spanning the widest possible range of longitudes are desired.
Here you will find images of Mars contributed by amateurs and professional, tools to aid you in planning your own Mars observations, current and past issues of the International Mars Watch Electronic Newsletter, and links to other Mars-relevant sites on the Internet.
When is all this happening?
The next opposition of Mars will be in November 2005 but the observing season spans a period of about five months before to five months after the opposition date. During this time the apparent size of Mars will increase from about 5" in diameter to about 20"! This means that Mars will be an impressive sight in telescopes of all sizes.
As we all acquire our images of the Red Planet, they can be uploaded to the official MarsWatch FTP site. This site is up and running, ready for your contributions. It will remain open throughout the entirety of 2005–6 at which point all the images will be collected into a single archive. This archive will be available from this site.
All the information you need will be here at this WWW site. There are links to the MarsWatch sites for the previous oppositions, as well as many other Mars related links. Breaking news will be published here, at the top of the page once things get underway, and in the MarsWatch Electronic Newsletter. If you are interested in receiving the newsletter, please subscribe!
As for where to make Mars observations the answers is: Anywhere! Mars changes on short timescales so it is important to observe it throughout the year. Mars also rotates once every 24 hours so having observers spread throughout the world will allow us to monitor Mars at all longitudes throughout a single Mars "day".
Mars is the subject of intense study by NASA and NASA funded researchers. Although we have learned much about the Red Planet, there is still much to learn How much water is there on Mars? How does this water move about? What about the possible "warm, wet Mars"? Are the dry river beds from surface or underground flows?
To help answer these questions NASA initiated an intense program of robotic missions including the Mars Pathfinder with Sojouner Rover, the Mars Global Surveyor (MGS) and Mars Odyssey orbiters and the Mars Exploration Rovers (MER) Spirit and Opportunity. The European Space Agency currently has the Mars Express orbiter. We telescopic observers will be looking at the planet to complement all this spacecraft work, specifically to help get study the changes in Mars throughout a single "day". We will also help identify and track the dust and ice clouds. The MarsWatch program is designed to create a place where all observers can share their knowledge and images throughout the observing season. Our goal will be to create a global view of Mars every day. The images submitted will then be available to the entire observing community (and the public in general) for comparison and interpretation.
How can I participate?
Observe! In order to create the best possible set of comparable images, observations through standard B, V, R, and I filters is encouraged. Once you have your images, and a short description of the image, submit them here for everyone to see and use in their research and work. You can get full instructions on the official MarsWatch FTP site.
Prior to observing, if you can, submit your observing plan so others will know what sort of coverage you hope to get so they can plan coordinating observations. You can e-mail your plans, and any other comments, to David Klassen at Rowan University otherwise known as "he who will maintain this site and publish the MarsWatch Newsletters". Your observing plans, and comments if you wish, will be put into the next Newsletter and on this site.