Using the Web

Go to the U.S. Naval Observatory website (USNO “Data Services,” at Look up the times for sunrise and sunset for your location for the current week. (You can change the dates one at a time, or bring up a table for the entire month.) How are the times changing from one day to the next? Are the days getting longer or shorter? Bring up the “Duration of Days/Darkness Table for One Year” page for your location. When do the shortest and the longest days occur? Look up a location in the opposite hemisphere (Northern or Southern). When are the days shortest and longest?
Go to the “Earth and Moon Viewer” website ( Under “Viewing the Earth,” click on “latitude, longitude and altitude” and enter your approximate latitude and longitude, and 40,000 for altitude; then select “View Earth.” Are you in daytime or nighttime? Now play with the locations; keep the same latitude but change to the opposite hemisphere (Northern or Southern). Is it still night or day? Go back to your latitude, and this time enter 180 minus your longitude, and change from west to east, or from east to west, so that you are looking at the opposite side of Earth. Is it night or day there? What do you see at the North Pole (latitude 90° north) and the South Pole (latitude 90° south)? At the bottom of your screen you can play with the time. Move back 12 hours. What do you observe at your location and at the poles?
Go to the U.S. Naval Observatory website (USNO “Data Services,” at Look up the Moon data for the current day. When will it rise and set? What is the phase? How will it change over the next 4 weeks. Enter one day at a time or look at the yearlong tables for moonrise and moonset and for the dates of primary phases. What time of day does a quarter Moon rise? When (in what phases) can you see the Moon in the daytime?
Using the times of moonrise and moonset that you located in question 58, make a plan to observe the Moon directly at least once a day for a week. Take a picture of the Moon (or make a sketch) every day. How is the brightness of the Moon changing? If it’s daytime, how far is the Moon from the Sun in the sky? If it’s nighttime, are the stars that are near the Moon in the sky the same every night?
Go to the “NASA Eclipse” website ( When is the next lunar eclipse? Will it be visible at your location if the skies are clear? Is it a total or partial eclipse? How about the next solar eclipse? Will it be visible at your location? Compare the fraction of Earth that the solar eclipse will affect with the fraction for the lunar eclipse. Why are lunar eclipses visible in so many more locations?

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