Neptune is the eighth and farthest known planet from the Sun in the Solar System. It is the fourth-largest planet by diameter and the third-largest by mass. Among the giant planets in the Solar System, Neptune is the most dense. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth and slightly larger than Neptune.[c] Neptune orbits the Sun once every 164.8 years at an average distance of 30.1 astronomical units (4.50×109 km). Named after the Roman god of the sea, its astronomical symbol is ♆, a stylised version of the god Neptune's trident. 

Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical prediction rather than by empirical observation. Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet. Neptune was subsequently observed with a telescope on 23 September 1846 by Johann Galle within a degree of the position predicted by Urbain Le Verrier. Its largest moon, Triton, was discovered shortly thereafter, though none of the planet's remaining known 14 moons were located telescopically until the 20th century. The planet's distance from Earth gives it a very small apparent size, making it challenging to study with Earth-based telescopes. Neptune was visited by Voyager 2, when it flew by the planet on 25 August 1989. The advent of Hubble Space Telescope and large ground-based telescopes with adaptive optics has recently allowed for additional detailed observations from afar.
Where did Neptune get its name from?
What is its astronomical design supposed to imply?
Was it discovered accidentally by telescope?
How was it found?
Who did that?
What made him think there was another planet out there?
How many other planets were discovered this way?
Who first saw it through a telescope?
Was it close to where he thought it would be?
Does it have any moons?
More than ten?
Which is the biggest of them?
Is the planet easily seen through a telescope?
Have any man made objects gotten close to it?
Which?
Is Neptune the seventh planet from the sun?
Is it a fairly dense planet?
How many earth years is one Neptune year?
Is there a similar planet to Neptune?
Which one?
the Roman god of the sea
Named after the Roman god of the sea,
Neptune's trident.
 its astronomical symbol is ♆, a stylised version of the god Neptune's trident. 
No
Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical prediction rather than by empirical observation.
mathematical prediction
by mathematical prediction rather than by empirical observation
Alexis Bouvard
Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet
Unexpected changes in the orbit of Uranus
Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet.
One
and is the only planet in the Solar System found by mathematical prediction rather than by empirical observation
Johann Galle
Neptune was subsequently observed with a telescope on 23 September 1846 by Johann Galle within a degree of the position predicted by Urbain Le Verrier.
Yes
within a degree of the position predicted by Urbain
Yes
 Its largest moon, Triton, was discovered shortly thereafter, though none of the planet's remaining known 14 moons were located telescopically until the 20th century
Yes
remaining known 14 moons
Triton
Its largest moon, Triton
No
The planet's distance from Earth gives it a very small apparent size, making it challenging to study with Earth-based telescopes.
Yes
Neptune was visited by Voyager 2, when it flew by the planet on 25 August 1989.
Voyager 2
Neptune was visited by Voyager 2
No
Neptune is the eighth and farthest known planet from the Sun in the Solar System
Yes
Neptune is the most dense
164.8
Neptune orbits the Sun once every 164.8 years
Yes
than its near-twin Uranus
Uranus
its near-twin Uranus