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Astronomy Simulator
The top level of the astronomy simulator: it gathers the sky view, the orbit view and the interstellar neighborhood map in one place, and compares sizes and distances against a Sun of radius one.
What each of the three views covers
The sky view fixes a city and a time and draws what the sky looks like from that spot, with constellations, the Moon and the planets above the horizon. It answers the question of what is visible tonight. The orbit view takes the same bodies and looks down on them from outside, showing the orbital motion itself rather than the appearance. The interstellar neighborhood map leaves the solar system behind and spreads the surrounding stars out in depth, at the distances they really occupy. The three screens differ in where you stand, not in what they describe.
Switching views and comparing sizes
The sub-tabs take you straight into each view, and the comparison on this page is still here when you come back. That comparison normalizes the Sun's radius to one, which puts the sizes of planets, dwarf planets and comets, and their distances from the Sun, on a single shared scale. Drag to move the display, use the wheel or a pinch to zoom, and select an item to see where it falls along that scale. Nothing needs installing, and the same gestures work on a phone.
What the numbers rest on
Positions across the views are approximations based on J2000 mean orbital elements. The size and distance comparison is likewise normalized against the Sun, so it is a tool for grasping the difference in scale rather than for reading off absolute figures. Each view is tuned to the accuracy that teaching and reference need, so for anything that depends on exact timing, such as planning an observation, check an official prediction from NASA or a similar source as well.
Which view to start from
If the goal is to find something in tonight's sky, start with the sky view. If the question is why the planets move the way they do, or where a comet comes from and where it goes next, move to the orbit view. When you start wondering how far away the stars themselves are and how they are arranged around the Sun, the interstellar map is the one that answers. If scale is the thing you are after, stay on this page and work through the size comparison first. Background on individual objects lives in the site's encyclopedia, and recent happenings are written up in the sky news section.
Look it up here
- What stars are visible in the sky tonight? The sky map draws the stars and planets standing above your horizon right now, for your own time and place. Show it here →
- In what order do the planets orbit the Sun? Eight planets from Mercury out to Neptune circle the Sun at their own speeds, seen from above the orbital plane. Show it here →
- How does the Moon go around the Earth? The Moon circles Earth every 27.3 days at some 380,000 km, riding along with it on the trip around the Sun. Show it here →
- Where is Jupiter in the sky tonight? Tonight's view marks the compass direction and altitude of Jupiter, which sits 5.2 AU out and orbits once in twelve years. Show it here →
- How are the stars around the Sun actually spread out? Nearby stars sit at their true three-dimensional positions by distance, not in the flat patterns we trace from Earth. Show it here →
FAQ
Which views does it include?
Three: the sky view, the solar system orbit view, and the interstellar neighborhood map, each reachable from a sub-tab. This top page itself holds the size and distance comparison built on a Sun of radius one, which is a good place to get a sense of overall scale before splitting off into the individual views.
What does normalizing to a Sun radius of one mean?
It means the Sun's radius is treated as the unit, and every other size and distance is expressed as a multiple of it. Written in kilometres the figures differ by too many orders of magnitude to compare at a glance; expressed against one shared unit, the gaps between planets, dwarf planets and comets become readable on a single screen.
Do I need to install anything?
No. Open the address in a browser and it runs, and on a phone the same drag and pinch gestures apply. Moving between views happens through the sub-tabs, so you can keep exploring without leaving the page.