Astronomy tools

Free calculators that run in your browser: what is up tonight, telescope magnification, Moon phases and more.

What's in the sky tonightSunset, darkness, the Moon and visible planets for your city.Telescope magnification calculatorMagnification, field of view, exit pupil and limits for any eyepiece.Moon phase calendarEvery night's Moon for any month, with exact quarter times.Your weight and age on other planetsHow much you would weigh and how old you would be on each world.How long would it take to get there?Travel times to the Moon, planets and stars by car, jet, probe and light.

Everything is calculated in your browser. Your location is used only on this page and is never sent to us.