This website provides an easy-to-understand look at our weather system. Topics covered include the atmosphere, the water cycle, storms, ice and snow, weather forecasting and Earth's changing climate. There are features on ozone depletion, global warming, El Nino and La Nina. An activity allows users to identify cloud formations associated with tornadoes, complete with photographs. There is also a ... Full description.

The United States Naval Observatory (USNO) data services page provides tools for calculating the times of sunrise, sunset, moonrise, moonset, and civil twilight, as well as rise and set times for major solar system objects and bright stars. There is a section of lunar data that includes dates of its primary phases, a tool for calculating the illuminated fraction, and a graphic that displays the apparent ... Full description.

This tool allows users to find when planets are visible in a given year. The years covered by this site are 1900 to 2100. The positions given are for the 1st of the month, at 9 pm, and generally hold true for the entire month. Positions are noted by which constellation the planet is located in. The planets given are Venus, Mars, Jupiter, Saturn, Neptune, Uranus, and Pluto. Additional comments for ... Full description.

This interactive tool allows users to view sky maps for different latitudes during different times of the year. It produces a printable sky map for any given latitude, month, and time. The map indicates direction (north, south, east, west), constellations (which can be clicked for detailed information), and other objects within the sky, such as galaxies and Messier Objects. This website is part of ... Full description.

This program simulates the collision of an asteroid or a comet with any planet in Solar System. Users can pick one of the nine planets in the Solar System or the Earth's Moon, choose the composition and diameter (size) of the projectile, and choose the speed of the projectile. Approximate results are returned. Full description.

At this site 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. Images can be generated based on a full-colour image of the Earth by day ... Full description.

This mapping tool allows users to generate Earthquake Probability Maps (EPMs) for a region within 50 kilometers of a location specified by latitude and longitude or by ZIP code. The maps are color-coded; higher earthquake probabilities are indicated by orange and red colors, while lower probabilities are indicated by green or blue. Fault traces are marked in white; rivers are in blue. The maps are ... Full description.

This applet demonstrates how altitude impacts the distance a fly ball travels in a ballpark. Users choose a city (altitude), ball speed, and angle of departure with respect to the ground, and the program depicts the ball's trajectory. Full description.

This interactive calculation tool allows users to enter their birth dates and discover what their ages would be on other planets. It is accompanied by a discussion of how time intervals are defined and how the Earth's rotation and its revolution about the Sun define our terrestrial seconds, minutes, days, and year. There is also a table showing the rotation and revolution periods of the planets and ... Full description.

This Java applet creates a model of a solar system with user-defined data. Users can create a solar system with up to four planets, choosing the star type at the center of the solar system, planet name, size, eccentricity of orbit and distance from the star. This site then calculates these factors to produce a graphic of the solar system with details about each planet such as its atmosphere, temperature, ... Full description.