5 Classical Planets?

Question

I know that there are 5 classical planets, but some that are not in that group can still be seen from earth (thats what i was told) If they can be seen why aren't they consider in that group of classical planets?

=)

Answer 1

The 5 classical planets are: Mercury, Venus, Mars, Jupiter, and Saturn.  Uranus can be seen with the naked eye, but just barely, so it wasn't discovered until the 18th century.  Neptune requires a telescope to see, so it wasn't discovered until the 19th century.  Pluto, of course, is out of the question without a powerful telescope.

Answer 2

The key point that you are missing is seen from earth with the naked eye. That rules out Uranus and Neptune, which require a telescope to see.

Answer 3

The 7 classical planets are Mercury, Venus, Mars, Jupiter, Saturn, the Sun and the Moon.  These can all be seen naked eye.  You have to wait until morning to see the Sun.  Please don't look at the Sun without proper protection.

Uranus was discovered by telescope.  However, from a dark sky site, it can be seen naked eye.  It wasn't, as far as we know.  Since the ancients didn't know about it, it's not a planet.

The ancients had this idea that 7 was somehow a perfect number.  So, perhaps they stopped looking for planets.

Ceres was once a planet - 1800 to about 1850.  It gets naked eye from time to time.  Currently, it's magnitude 5.9, for example.  You might be able to spot it from a dark sky site, in the morning, an hour or so before sunrise. Ceres was also discovered by telescope.

Answer 4

The only other one which can be seen with the naked eye is Uranus. And that is so extremely faint, even under the best circumstances, that it was never recorded.  In addition, its position changes very slowly against the stars.

Neptune, of course, is far below the naked eye threshhold.

Okay, I get it now.  Somebody, no doubt using multiple IDs, has been going down my list giving three thumbs down to all my answers lately.  Get a life.

Answer 5

Although it is possible to see Uranus in a very dark sky with good eyes, it is just at the limit of what can be seen without a telescope. It is not obvious at all. In comparison, the dimmest classical planet, Saturn, is brighter than all but the brightest stars. Uranus was simply not noticed before telescopes were invented.