Bad Astronomy - "Examples of mistakes in the media, movies, and on television are found on this searchable site. They are utilized as the method to explain actual science. Author is an astronomer at NASA's Goddard Space Flight Center.
Basics of Space Flight - This is a training module designed primarily to help JPL operations people identify the range of concepts associated with deep space missions and grasp the relationships these concepts exhibit for space flight. It also enjoys growing popularity among high school and college students, as well as faculty and people everywhere who are interested in interplanetary space flight.
Earth and Moon Viewer - You can view either a map of the Earth showing the day and night regions at this moment, or view the Earth from the Sun, the Moon, the night side of the Earth, above any location on the planet specified by latitude, longitude and altitude, from a satellite in Earth orbit, or above various cities around the globe
Earth from Space - Site presents the NASA Space Shuttle Earth Observations Photography database of over 375,000 images. A clickable map allows you to view landscapes, hurricanes and weather, water habitats, and other geographic features.
Explore the Moon -What's it like to walk on the moon? Join the Apollo astronauts on the surface in this series of stunning 360-degree panoramas, one each from the six successful Apollo moon landings. Shot by the astronauts themselves during their historic moonwalks, these QuickTime images capture the magic and mystery of the moon like no standard photograph can.
GRIN: Great Images in Nasa - Site provides a collection of over a thousand images of significant historical interest scanned at high-resolution in several sizes. This collection is intended for the media, publishers, and the general public looking for high-quality photographs.
Human Space Flight: Apollo History - This NASA site offers the history of the Apollo program. The Apollo program was designed to land humans on the Moon and bring them safely back to Earth. Details, facts and information about all 11 of the Apollo program space flights, including those flights in earth or lunar orbit and those that actually landed on the Moon.
Inconstant Moon: multimedia tours of the lunar surface - "Explore the Moon... discover its dramatic features and phenomena - often beautiful, sometimes bizarre, always changing. Inconstant Moon will take you on a new tour each night, with maps, photos, explanations, animations, selected links and even music!"
Lunar Orbiter Photographic Atlas of the Moon - "The definitive reference manual to the global photographic coverage of the Moon. The images contained within the atlas are excellent for studying lunar morphology because they were obtained at low to moderate Sun angles. This digital archive consists of the complete set of 675 plates. Images in the archive have been enhanced to display the best photo quality possible."
MAP - The Microwave Anisotropy Probe - NASA site presents information on a mission that will measure the temperature of the cosmic background radiation over the full sky with unprecedented accuracy. This map of the remnant heat from the Big Bang will provide answers to fundamental questions about the origin and fate our our universe.
NASA: Earth Observatory - The purpose of NASA's Earth Observatory is to provide a freely-accessible publication on the Internet where the public can obtain new satellite imagery and scientific information about our home planet. The focus is on Earth's climate and environmental change.
The Nine Planets - "This website is an overview of the history, mythology and current scientific knowledge of the planets, moons and other objects in our solar system. Each page has our text and NASA's images, some have sounds and movies, most provide references to additional related information."
Planet Finder - This applet shows the locations of the planets, stars, moon, and sun in the sky from any location and for any date and time.
Planet Quest: The Search for Another Earth - This site by NASA and the Jet Propulsion Laboratory details their search for another Earth -- entailing light-seeking interferometers, interstellar telescopic wizardry, and scientific passion that aims to rejuvenate space program.
Planetary Fact Sheets - This site by NASA's National Space Science Data Center provides fact sheets for every planet and for many minor bodies, including information on mass, rotation and revolution periods, atmospheric composition, magnetospheric information, and much more.
Planetary Photojournal, The - For for an out-of-this-world journey, take a pictorial tour of the solar system, courtesy of NASA. The Planetary Photojournal also lets you keep track of new image releases.
Potentially Hazardous Asteroids - " Anew NASA survey has pinned down the number of asteroids that could pose a collision threat to Earth in what scientists say is the best estimate yet of the potentially dangerous space rocks."
SEDS: Students for the Exploration and Development of Space - "SEDS is an independent, student-based organization which promotes the exploration and development of space. SEDS pursues this mission by educating people about the benefits of space, by supporting a network of interested students, by providing an opportunity for members to develop their leadership skills, and inspiring people through our involvement in space-related projects. SEDS believes in a space-faring civilization and that focusing the enthusiasm of young people is the key to our future in space."
Satellite Tracking - NASA's J-Track lets you follow a fairly large list of satellites and space craft. With real-time maps.
Sky Map - Produce sky maps for any time and date, viewpoint, and observing location. If you enter the orbital elements of an asteroid or comet, Site will compute its current position and plot it on the map. Each map is accompanied by an ephemeris for the Sun, Moon, planets, and any tracked asteroid or comet.
Sky & Telescope Magazine - for the more technically advanced reader, but the Home Page is written so that anyone can understand it.
Skywatching - This site by Space.com offers spectacular images in the latest top space stories.
Solar System Exploration - Solar System Exploration is one of four space science themes for the Office of Space Science at NASA. This site is your launching pad to find out more about the programs and people in them.
Solar System Simulator - allows you to view any planet as seen from any other planet. Gaze at Jupiter from Venus or Earth from Pluto
Space.com - A definitive Web site dedicated to space and all space-related subjects. It focuses on news, information, education and entertainment.
Space Environment Center - "This National Oceanic and Atmospheric Administration site, the official source of space weather alerts, warnings, and forecasts, provides current information on geomagnetic storms, solar winds, solar flares, and aurora activity."
SpaceWeather.com - News and information about meteor showers, solar flares, auroras, and near-Earth asteroids. Daily monitoring of solar flares, geomagnetic storms, Earth's aurora, and all forms of space weather.
Tonight's Sky - Each day's segment is designed to guide your eye to something you can see that night, or the next morning before dawn. It might be a constellation, a star, or a planet. Or it might be a celestial event, such as an eclipse.
Virtual Trips to Black Holes and Neutron Stars - site takes you on a fantasy trip into a black hole and neutron star. The movies are computer animations, and are scientifically accurate. There is also a published paper from the American Journal of Physics, geared for college students.
Visible Earth - a searchable directory from NASA of images, visualizations, and animations of the Earth.