Deep Time
See where the Sun, the Moon and the planets stand at this very moment, from your own place. Then drag the timeline back to the Moon's birth and watch the day grow longer.
Mac App Store coming soon
Solar and lunar eclipses happen in the scene and in the sky of your place. In totality the sky goes dark and the corona appears; the eclipsed Moon turns copper red. The sky calendar says what you can see of each one where you are.
By day the blue sky and the Sun's path, at dusk the colours of twilight, at night about 5,000 stars, the Milky Way, the 88 constellations and the bright planets by name. During a meteor shower, meteors fall at the rate one person would see.
Drag the timeline and the continents move: Pangaea forms and breaks apart, ice comes and goes. Temperature, sea level and the variety of life run along in the chart, with the five mass extinctions.
4.5 billion years ago the Moon had just formed and stood many times closer. A day lasted under six hours, a year had more than 1,400 of them, and the Sun shone at 72 % of today's brightness.
Oxygen, carbon dioxide and methane, each with a best estimate and the range of what is known. The app judges the air as a mountaineer would: thin, deadly, or richer than today, as in the coal swamps 300 million years ago.
Mercury, Venus, Mars, Jupiter and Saturn through the year: evening or morning, how long, how bright and in which constellation. Oppositions and close pairs are in the sky calendar.
The orbit with its months, solstices and equinoxes, nearest and farthest point. Charts show the daylight and the three twilights, the Sun's height at noon, the Moon's phase and distance, and the analemma.
Choose a city from the list inside the app, type coordinates or click the globe. Then pick any moment of any year and watch day and night pass over your place.
Every curve names its source and shows a range where the past is uncertain. Near the present, clock times are good to well under a minute; far from today the app says so.
The app makes no network connections. Everything is calculated on your Mac, and it does not use Location Services. Links to Wikipedia open in your browser.