What is the correct order of planets from smallest to largest?

Mercury, Venus, Mars, Earth, Uranus, Neptune, Saturn, Jupiter Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn, Jupiter Mars, Mercury, Earth, Venus, Neptune, Uranus, Saturn, Jupiter Mercury, Mars, Earth, Venus, Neptune, Uranus, Jupiter, Saturn

Which planet is the densest in the solar system?

Mercury Jupiter Earth Neptune

Which planet is the least dense in the solar system?

Jupiter Uranus Neptune Saturn

Which planet has the most known moons?

Saturn, because it is the second largest Uranus, because of its unusual tilt Jupiter, with 95 confirmed moons Neptune, because of its distant orbit

Which two planets rotate in the retrograde direction (opposite to most other planets)?

Mercury and Mars Jupiter and Saturn Neptune and Saturn Venus and Uranus

When viewed from above Earth's north pole, in which direction do all planets orbit the Sun?

Clockwise Counterclockwise Some go clockwise and some counterclockwise They orbit in whichever direction gives the shortest path

How was Neptune discovered — and what makes this discovery scientifically remarkable?

Neptune was spotted by accident during a routine sky survey A space probe first detected Neptune before telescopes could see it Neptune was found through mathematical prediction: astronomers noticed Uranus was not following its predicted orbit and calculated where an unseen planet must be pulling it off course Neptune's radio emissions were detected before it was seen visually

Besides Earth, which three locations in the solar system are considered the best candidates for finding life?

Venus, Titan, and Io Mars, Europa (Jupiter's moon), and Enceladus (Saturn's moon) Mercury, Jupiter, and Saturn Pluto, Triton, and Titan

Which planet among the eight has the most eccentric (least circular) orbit?

Mars Pluto Mercury Neptune

Have all eight planets been visited by at least one spacecraft?

No — scientists have only sent spacecraft to the four inner planets No — Neptune and Uranus are too far away for any spacecraft to reach Yes — every planet has been visited by at least one spacecraft, though Uranus and Neptune have only had one flyby each Only the planets up to Saturn have been visited

Earth is the only planet confirmed to support life. What combination of factors makes Earth uniquely suited for life?

Earth is the largest terrestrial planet, so it has the best conditions Earth is closest to Jupiter, which shields it from impacts The right distance from the Sun, a protective magnetic field, liquid water, a stable atmosphere, and a large stabilizing moon all work together Earth was specifically created with life in mind