Uranus if you're going by mass, Neptune if you're going by radius/volume.
NeptuneNeptune is the fourth largest planet out of the eight in our solar system, after Jupiter, Saturn and Uranus.
Your question could mean there is a name "4TH planet" and asking about what it is. If you mean "what is the planet which is the fourth one away from the Sun ?" your answer would be Mars.
The seventh planet from the sun is Uranus. It is the third largest planet in our solar system and the fourth most massive.
It is the third-largest by mass, but the fourth-largest by size.
No. Neptune is the fourth largest planet in out solar system, smaller than Uranus, Saturn, and Jupiter. The largest in our solar system is Jupiter.
Neptune is the fourth largest planet out of the eight in our solar system, after Jupiter, Saturn and Uranus.
No, Neptune is not the smallest planet in our solar system. In fact, Neptune is the fourth largest planet by diameter, after Jupiter, Saturn, and Uranus. Mercury holds the title of being the smallest planet in our solar system.
No, Saturn is the second largest planet of our solar system, after Jupiter. It is larger than Neptune.
Jupiter is the largest planet in the solar system.
The largest object in the solar system is not a planet. It is the Sun. The largest planet is Jupiter.
Neptune is a big planet but jupiter is the biggest planet in the solar system and Mercury is the smallest.
No Neptune is the fourth largest planet, not the third. It is however, the third most massive as it is slightly smaller than Uranus, but about 15% denser.