What Are the Solar System Planets in Order?

Over the past 60 years, humans have begun to explore oursolar systemin earnest. From the first launches in the late 1950s until today, we've sent probes, orbiters, landers, and even rovers (like NASA'sPerseverance Roverthat touched down on Mars in February 2021) to every planet in our solar system. But can you name all eight of thoseplanets in order? (Yes, there are only eight – not nine.Pluto got "demoted"in 2006.) And can you put them in the correct order?

In case you're a little rusty, we'll break down some common ways to order the planets plus a few tricks to help you remember them going forward. Let's start with the distance from thesun.

The most common way to order the planets is by theirdistance from the sun. Using this method, the planets are listed in the following order:

Planets in Order From the Sun

Mercury- 0.39 AU from the sun
Venus- 0.72 AU
Earth- 1.00 AU
Mars- 1.52 AU
Jupiter- 5.20 AU
Saturn- 9.54 AU
Uranus- 19.20 AU
Neptune- 30.06 AU

AU stands for astronomical units – it's the equivalent to the average distance from Earth to the sun (which is why Earth is 1 AU from the sun). It's a common way astronomers measure distances in the solar system that accounts for the large scale of these distances. To put it another way, Mercury, which is closest, is 35.98 million miles from the sun, while Neptune, the farthest, is 2.79billionmiles from the sun. Earth is 92.96 million miles from the sun.

How to Remember the Order of the Planets

There are many handy expressions to remember the order of the planets. These are typically mnemonics which use the first letter of each planet's name to come up with a phrase that's easier to remember.

Here are some of themost common (and silliest) ones:

My Very Excellent Mother Just Served Us Noodles (or Nachos)
My Very Easy Method Just Speeds Up Names
My Very Expensive Malamute Jumped Ship Up North

In each case, "M" stands for "Mercury," "V" for "Venus," and so on. You can also try to remember them with a few rhyming verses:

Amazing Mercury is closest to the Sun, Hot, hot Venus is the second one, Earth comes third: it’s not too hot, Freezing Mars awaits an astronaut, Jupiter is bigger than all the rest, Sixth comes Saturn, it's rings look best, Uranus sideways falls And along with Neptune, They are big gas balls.

Finally, if you are musically inclined, there are a few songs that may help you remember. Two popular ones areMr. R's Planet SongandThe Planet Songfrom Kids Learning Tube.

You Can Order the Planets in Other Ways

While most people want to know the order of the planets by distance, there are other ways to order the planets that you might be curious about.

For example, if you order the planets by size (radius)从biggest to smallest, then the list would be:

The Planets in Order by Size

Jupiter (43,441 miles/69,911 kilometers)
Saturn (36,184 miles/58,232 km)
Uranus (15,759 miles (25,362 km)
Neptune (15,299 miles/24,622 km)
Earth (3,959 miles/6,371 km)
Venus (3,761 miles/6,052 km)
Mars (2,460 miles/3,390 km)
Mercury (1,516 miles/2,440 km)

Or you could order the planets by weight (mass). Then, the listfrom most massive to least massivewould be: Jupiter (1.8986 x 10²⁷kilograms), Saturn (5.6846 x 10²⁶kg), Neptune (10.243 x 10²⁵kg), Uranus (8.6810 x 10²⁵kg), Earth (5.9736 x 10²⁴kg), Venus (4.8685 x 10²⁴kg), Mars (6.4185 x 10²³kg), and Mercury (3.3022 x 10²³公斤)。有趣的是,海王星质量超过Ura所言nus, even though Uranus is larger! Scientists can't put a planet on a scale, soto determine mass, they look at how long it takes nearby objects to orbit the planet and how far from the planet those objects are. The heavier the planet, the stronger it pulls on nearby objects.

Planets With the Most Moons

Finally, a fun way to order the planets is bythe number of moonsthey have. We'll start with the planet that has the most:

Saturn (146)
Jupiter (95)
Uranus (27)
Neptune (14)
Mars (2)
Earth (1)
Venus and Mercury (both zero)

(Note that these numbers include provisionalmoonsthat are still being confirmed by astronomers.)

In short, there are a number of ways to order and reorder the planets based on different facts about them; as long as you remember there are eight in total that's what counts. (Sorry,Pluto!)

Is Pluto a Planet?

Speaking of Pluto, what's the deal? After its discovery in 1930, Pluto was classified as a planet. However, in 2006, the International Astronomical Uniondowngraded Plutofrom "planet" to "dwarf planet." This is because the definition of a planet means that it has cleared its orbit of other objects (which Pluto has not done, as it shares its space with manyKuiper Beltobjects). Pluto is one of five dwarf planets in our solar system – and it's not even the largest one (that'sEris).