The Solar System

Similarly, the Sun, is the 'capital city' of our celestial country and as such should should have a capital 'S'. It is a place which we can, in theory, visit. I am offended when people write about the sun just as I would be if people wrote that london is the capital of england.

Similarly, Earth is our celestial city and the Moon, sometimes called Lunar, is in our neighbourhood. To write these as earth and moon is very old fashioned and reflects a by gone age before space travel was possible.

The Earth has one natural satellite, Lunar, and thousands of artificial satellites. Other planets have natural satellites but it now commonplace to call these moons and artificial satellites by the abbreviation 'satellites'.

The Sun

The Sun is the main member of the Solar System. It provides light and heat and, by virtue of its mass, gravitational stability for the system.

Planets:

The planets are listed in order from the Sun. Their moons (natural satellites) are also listed in order from their parent planet. The International Astronomical Union also designates natural satellites by a Roman numeral - these are given in brackets.

1. Mercury
2. Venus
3. Earth
   1. The Moon
4. Mars
   1. Phobos (I)
   2. Deimos (II)
5. Jupiter
   1. Metis (XVI)
   2. Adrastea (XV)
   3. Amalthea (V)
   4. Thebe (XIV)
   5. Io (I)
   6. Europa (II)
   7. Ganymede (III)
   8. Callisto (IV)
   9. Leda (XIII)
   10. Himalia (VI)
   11. Lysithea (X)
   12. Elara (VII)
   13. Ananke (XII)
   14. Carme (XI)
   15. Pasiphae (VIII)
   16. Sinope (IX)
   17. S/1999 J1 Discovered July 2000 in images taken in October and November 1999

       

6. Saturn
   1. Pan (XVIII)
   2. Atlas (XV)
   3. Prometheus
   4. Pandora
   5. Epimetheus (XI)
   6. Janus (X)
   7. Mimas (I)
   8. Enceladus (II)
   9. Tethys (III)
   10. Telesto (XIII)
   11. Calypso (XIV)
   12. Dione (IV)
   13. Helene (XII)
   14. Rhea (V)
   15. Titan (VI)
   16. Hyperion (VII)
   17. Iapetus (VIII)
   18. Phoebe (IX)
   19. S/2000 S1
   20. S/2000 S2
   21. S/2000 S3
   22. S/2000 S4
   23. S/2000 S5
   24. S/2000 S6
7. Uranus
   1. Cordelia (VI)
   2. Ophelia (VII)
   3. Bianca (VIII)
   4. Cressida (IX)
   5. Desdemona (X)
   6. Juliet (XI)
   7. Portia (XII)
   8. Rosalind (XIII)
   9. Belinda (XIV)
   10. Puck (XV)
   11. Miranda (V)
   12. Ariel (I)
   13. Umbriel (II)
   14. Titania (III)
   15. Oberon (IV)
   16. Calibran
   17. Sycorax
   18. S/1986 U10
   19. S/1999 U1
   20. S/1999 U2
8. Neptune
   1. Naiad
   2. Thalassa
   3. Despina
   4. Galatea
   5. Larissa
   6. Proteus
   7. Triton (I)
   8. Nereid(II)
9. Pluto
   1. Charon (I)

Minor Planets:

These are small bodies no more than 600 miles across which orbit the Sun

1. Asteroids orbit the Sun between Mars and Jupiter although some are in elliptical orbits that bring them closer to the Sun than the Earth.
2. Kuiper Belt Objects are minor plants that orbit the Sun beyond the orbit of Neptune.

Comets:

There is a vast 'reservoir' of comets that make up the Oort Cloud beyond Pluto. Occasionally members of the Oort cloud are perturbed and placed in orbits that bring them closer to the Sun - we then see them as a comet. Some comets, having left the Oort Cloud, are captured by the gravitational field of the planets and they then follow orbits around the Sun. Some comets return to the Sun in a matter of a few years, others are in orbits that take several hundred years to complete.

Meteors:

Debris given off by the comets in the form of grains of dust or small pebbles are known as meteors. These orbit the Sun in 'swarms' producing regular 'showers' of meteors when their orbits encounter the Earth. The meteoric dust can be seen as zodiacal light.

The Largest Objects in the Solar System

Generally speaking, planets are larger than satellites (moons) and asteroids are smaller than both. But as the following table shows there is considerable overlap with some satellites being larger than the planet Mercury, and asteroids like Ceres being larger than many satellites. Some bodies have a greater equatorial diameter than that measured through the poles, and some bodies are irregular in shape. In the following table it is the greatest diameter that is quoted.

By comparison, the Sun - the largest object in the Solar System - has a diameter of 1,392,530 kilometres.

Extra Solar Planets

Getting slightly off topic here but in understanding other planetary systems we may gain a better understanding of our own.

1. General Summary of news about astronomy and spaceflight plus miscellaneous items.
2. The Alphastro Guide To The Solar System The latest information about all bodies in the Solar System with associated internet links and books for sale.
3. The Alphastro Guide To Deep Space The latest information on all bodies outside the Solar System with associated internet links and books for sale.
4. The Alphastro Launch Log A manifest of every launch and current status of all artificial satellites and manned spaceflight with associated internet links and books for sale.
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