"That Day" is a free Android app developed by c.guine that provides a wealth of information about any given date. After entering a date, the app provides the day of the week, as well as the Western and Chinese astrological signs and their respective trends. In addition, users can choose a desired location to view the time of sunrise and sunset, as well as the moon's position in both local and GMT time.

The app also provides dates of lunar cycles, as well as the dates of sun and moon eclipses around the selected date. Finally, "That Day" offers information about the Chinese, Christian, Muslim, Buddhist, and Jewish calendars. With all of these features, "That Day" is a comprehensive app for anyone interested in learning more about specific dates.