A live view of the solar system and planet positions
This site brings you face to face with the solar system as it is now... and also how it was and how it will be.
Have you ever wondered "Where are the planets right now?"
For people interested in astrology the positions and movements of the planets are very important and can give you a clue into how you are feeling and how your day is going to pan out. For astronomers, it's equally important to know where the planets are so that they can observe them. For others, getting an understanding of where the earth is in relation to the sun and moon and planets is just, well, sort of nice to know. If you've ever sat outside at night and got into an discussion about whether that bright star is actually a planet, and if it is - "Which planet is it?", then this site might help narrow down the options!
This online orrery (Note: an orrery is a machine that shows the positions of the planets) will hopefully help you to understand what's going on out there.
What is it all about?
Our view of the Solar System - Getting Oriented
The flash application above plots the position of the earth and planets using data from this NASA's JPL website and is accurate between 3000BC and 3000AD. It shows a "plan view" of the planets laid out in the plane of the ecliptic (the flat plane in which all the planets move about the sun).
As you may know, the earth's axis is tilted over by 23.4 degrees and always points at the star known as the North Star. The image is arranged so that the earths north pole always tilts towards the top of the screen, and the south pole always towards the bottom. This means that during the summer months of the northern hemisphere the north pole is pointing more towards the Sun and so the earth is shown below the Sun. During the summer months of the southern hemisphere, the south pole points towards the Sun and so the earth is shown above the sun.
Unlike other online orreries in which you can look at the solar system from all angles, this site always shows the same view to try and help you keep your orientation. A north/south control allows the view to be changed from looking at the northern hemisphere to looking at the southern hemisphere. This control helps when trying to relate the positions of the planets in the night sky with what you are seeing in this app. In both views the north pole is kept tilting towards the top of the screen.
Because the display is locked with north tilting upwards, it acts rather like a clock face in which one revolution of the earth is one year, and each of the constellations approximately map to months of the year with January being when the sun is mostly in Capricorn and December when the sun is mostly in Sagittarius.
The Zodiac, Equinoxes and Solstices and the seasons
Solstices and Equinoxes
|December Solstice||March Equinox|
|June Solstice||September Equinox|
The Zodiac display is centred on the earth and oriented to the fixed positions of the stars. This display shows in which sign of the zodiac the sun lies at any time. The sign of the sun at a persons birth is called that persons Star Sign.
The winter and summer solstices occur as the sun crosses the vertical zodiac line and the spring and autumn equinoxes when the sun crosses the horizontal zodiac line. So, to use our anti-clockwise clock analogy (e.g. with the app in northern hemisphere mode) the winter (December) solstice is when the earth is exactly at 12 o'clock from the sun, the spring (March) equinox is when the earth is at 9 o'clock from the sun, Summer (June) Solstice - its at 6 o'clock and Autumn (September) Equinox - its at 3 o'clock from the Sun.
The longest and shortest days occur at the Solstices. At the Equinoxes, the day is almost exactly the same (12 hours long) all over the world.
|UTC date and time of solstices and equinoxes|
The Zodiac - and "Hey... That planet is in the wrong place!"
The zodiac in the app always shows which sign of the zodiac the Sun is in. However it may not be correctly showing which sign each planet is in. "How can that be?" you may ask. The reason is that the app has a slider control which changes the orbits of the planets from a diagrammatical view (i.e. all the planets in nice neat, equally separated, circular orbits) to a real view (i.e. all the planets in elliptical orbits with all the inner planets squashed in next to the sun and the outer planets being widely spaced). Only when the orbit realism slider is in the real position (against the tick icon) are all the planets definitely shown in the correct sign of the zodiac. For info on the app controls, click here.
This page by default shows the diagrammatic view. The Astrology page by default shows the real view.
The Zodiac - and "Hey... That planet is not in the star constellation shown!"
Sometimes people look into the night sky and expect that a planet shown to be in the zodiac sign of say "Cancer" will be sitting over the star constellation Cancer. This is not always true since zodiac signs and constellations do not match up one to one. The reason for this is that for one the constellations vary in size whereas zodiacs are all the same and two the constellations have moved (or rather the direction the earths north pole as moved) since astrology began. For a more detailed explanation on another site click here.
Which Planets are in Retrograde?
When the zodiac display is enabled, glowing indicators appear on those planets that are in retrograde - which means the planet is appearing to moving backwards from it's normal motion when viewed from earth. The image to the left shows Jupiter, Uranus and Neptune in retrograde because earth is speeding past on the inside orbit.
In Astrology, it is very important to know when the planets are in retrograde, and also when they stop and start to move forwards again (called the Stationary Direct) because it is believed that this motion can reverse and enhance the effect of the planet. For Astronomy, retrograde motions have no importance since they are simply the result of the motions of the planets relative to earth.
This software is still under development with additional features being added when we can. Please feel free to let us know if there are any features you would like added or questions about the solar system you would like answered, or give us any comments on the application.
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Other Free Online Orreries and Solar System Simulations
For some reason 2 of the 3 online orreries I used to list here are no longer running which is a real shame.
Anyhow, until I find some more good online orreries out there here is a really good one:
With lots of 3D features - and obviously more to come, this applications allows a full exploration of the solar system and it's bodies. It also allows you to see all the stars and constellations. Very impressive. Only slight downside is that that there are quite a few things to learn in order to use it fully, but otherwise really good fun.