Explore the Solar System Through Time
Planets are constantly changing position, distance, apparent size and brightness. An ephemeris tells us how those properties change with time.
Four ways to follow a Solar System object
5 September 2026
Compare the brightness, distance, apparent size and sky position of Solar System objects on any date.
| Object | Magnitude | Distance | Apparent size | RA | Dec |
|---|---|---|---|---|---|
| Sun | -26.72 | 1.008590 AU | 1,903.38″ | 10h 53m 57.5s | +07° 01′ 23.8″ |
| Moon | -9.84 | 0.002471 AU | 1,939.97″ | 05h 19m 19.8s | +28° 01′ 16.0″ |
| Mercury | -1.08 | 1.377720 AU | 4.89″ | 11h 24m 11.2s | +05° 15′ 38.9″ |
| Venus | -4.66 | 0.524227 AU | 31.86″ | 13h 30m 10.1s | −13° 37′ 52.7″ |
| Mars | 1.25 | 1.825730 AU | 5.12″ | 07h 07m 46.4s | +23° 07′ 16.7″ |
| Jupiter | -1.81 | 6.035800 AU | 31.96″ | 09h 07m 10.1s | +17° 05′ 28.7″ |
| Saturn | 0.46 | 8.280770 AU | 19.40″ | 00h 52m 13.9s | +02° 42′ 12.7″ |
| Uranus | 5.70 | 19.165000 AU | 3.65″ | 04h 13m 38.8s | +21° 01′ 53.4″ |
| Neptune | 7.68 | 28.791600 AU | 2.36″ | 00h 13m 56.5s | — |
| Ceres | 9.08 | 2.920300 AU | 0.45″ | 06h 34m 07.4s | +22° 51′ 08.6″ |
| Vesta | 7.00 | 1.475710 AU | 0.49″ | 01h 55m 43.1s | — |
| Pluto | 14.51 | 34.633200 AU | 0.09″ | 20h 25m 44.0s | −23° 39′ 06.8″ |
Values are read from the JPL-derived ephemeris data used throughout Show Me The Sky.
Choose an object and explore
How does it change?
Venus — Magnitude
What do these parameters tell us?
Brightness and apparent size
A planet's appearance changes as both its distance and geometry relative to Earth and the Sun change.
The magnitude scale describes apparent brightness, while angular size describes how large an object appears in the sky.
Distance and elongation
One astronomical unit (AU) is approximately the mean Earth–Sun distance.
Elongation measures the apparent angular separation between an object and the Sun. It is especially useful when considering the visibility of Mercury and Venus.
The Solar System is a moving system
A planet does not have one fixed distance, apparent diameter or brightness. Those quantities continually change as Earth and the other planets move around the Sun.
Ephemerides turn that orbital motion into predictions we can use to plan observations and understand what we see through a telescope.
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