How Big is the Moon?

The Moon is the only natural and permanent satellite of Earth. Some planets have two moons, like Mars, others have tens of moons, such as Jupiter, while the planet with the most moons is Saturn, which has 82 moons.

Moons vary in size, shape, and composition, and our Moon is in the top 10 list of the biggest satellites in our Solar System. How big is the Moon? 

Our Moon has a mean radius of 1,737 kilometers / 1,079 miles, while its polar radius is 1,736 km / 1,078 mi, and its equatorial radius is 1,738 km / 1,079 mi.  The Moon’s diameter is 3,474 km / 2,158 mi, and it is the biggest Moon in the Solar System relative to the size of its planet.

When it comes to other satellites, the Moon is the fifth largest satellite in the Solar System. So let’s take a look at the top 10 biggest moons in the Solar System.

Top 10 Biggest Moons in the Solar System

The top 10 biggest moons in our Solar System are genuinely gigantic, with some of them being even bigger than some of the Solar System’s planets, like Mercury, or they make dwarf planets such as Pluto, Eris, Haumea, Makemake, or Ceres, look small.


Top 10 Biggest Moons in the Solar System
#Rank Radius Diameter Parent Planet
1.Ganymede 2,634 km / 1,636 mi 5,268 km / 3,273 mi Jupiter
2.Titan 2,574 km / 1,599 mi 5,149 km / 3,199 mi Saturn
3.Callisto 2,410 km / 1,497 mi 4,820 km / 2,995 mi Jupiter
4.Io 1,821 km / 1,131 mi 3,643 km / 2,263 mi Jupiter
5.Moon (Luna) 1,737 km / 1,079 mi 3,474 km / 2,158 mi Earth
6.Europa 1,560 km / 969 mi 3,121 km / 1,939 mi Jupiter
7.Triton 1,353 km / 840 mi 2,706 km / 1,681 mi Neptune
8.Titania 788 km / 489 mi 1,576 km / 979 mi Uranus
9. Rhea 763 km / 474 mi  1,527 km / 948 mi Saturn
10. Oberon 761 km / 472 mi 1,522 km / 945 mi Uranus

As, such the top ten biggest moons in the Solar System are Ganymede, Titan, Callisto, Io, Luna (Moon), Europa, Triton, Titania, Rhea, and Oberon.

Four of the biggest moons in our Solar System belong to the biggest planet in our Solar System, namely Jupiter. Those moons are Ganymede, Callisto, Io, and Europa.

Ganymede is the biggest moon in the Solar System, bigger than the planet Mercury and all the dwarf planets. At the same time, Io, Callisto, and Europa are smaller than Mercury but more prominent than all the dwarf planets.

Out of the remaining six, two of the biggest moons in the Solar System belong to Saturn, the second biggest planet in the Solar System, and they are Titan and Rhea.

Titan, like its parent planet, also ranks in the second place, being the 2nd biggest moon in the Solar System. It is also bigger than Mercury and all the other dwarf planets. Rhea, on the other hand, is bigger only than the dwarf planets Makemake and Ceres.

Out of the remaining four biggest moons in the Solar System, two belong to the ice giant Uranus, namely Titania and Oberon. Titania is smaller than Pluto but bigger than Haumea, Makemake, and Ceres. Oberon is bigger only than Makemake and Ceres.

The last two of the biggest moons in our Solar System are Earth’s Moon and Neptune’s moon Triton. Our Moon is bigger than Europa, and the dwarf planets Pluto, Eris, Haumea, Makemake, and Ceres. Triton is also bigger than all the dwarf planets.

How Big is the Moon in Comparison to Earth?

How does the Moon compare to Earth? Our Moon’s diameter is more than a quarter of Earth’s diameter, while its mass is 1/81 that of Earth’s. It basically weighs 80 times less than our Earth. The Moon’s radius is only 27% of our Earth’s radius. If our Earth were hollow, it would take around 50 Moons to fill it.

How Big is the Moon in Comparison to the United States?

The United States is 4,506 km / 2,800 mi wide when measured horizontally from the eastern seaboard to the west coast – West Quoddy Head in the east to the Point Arena in the West. Thus the Moon is smaller in diameter than the United States, however.

The United States is 2,545 km / 1,582 mi from north to south, and thus, the Moon is smaller across than the United States is wide.

Is the Moon the Size of Texas?

The state of Texas, from its farthest point East to West, is about 1,239 km /  770 mi. The diameter of our Moon is far greater, at 3,474 km / 2,158 mi; thus, the Moon is 2.8 times bigger than the state of Texas.

What if the Moon was Twice as Big?

If the Moon would be twice as big, then solar eclipses would be even more common. The path of totality would be significantly wider, maybe over 3,600 km / 2,000 mi – the wideness of the Moon’s umbra. Totality would last much longer, perhaps more than an hour.

During totality, the sky would be much darker than before, and annular solar eclipse would cease to exist. Tides would be significantly larger on our Earth, but this assumes the Moon would have the same mass. If it didn’t, then it is highly possible that it would collide with our Earth.

Is Russia Wider than the Moon?

The surface area of the Moon is equivalent to the surface area of Russia, the United States, and Canada combined. In terms of wideness, Russia has an east-west extent of around 9,000 km / 5,600 mi, and a north-south width of 2,500 to 4,000 km / 1,500 to 2,500 mi.

This means that Russia is wider than the Moon when compared from the east-west extent, but smaller in the north-south width.

How Long Would It Take to Walk Around the Moon?

If you could walk continuously at a speed of 3.1 mph, you could walk around the Moon in around 91 days / 2,188 hours. However, if we were to talk realistically, and include rests, sleep, eating time, flat levelness, and other things, it would probably take you around a year or less to walk around the Moon once.

How Many Moons Can Fit in the Sun?

The Sun is gigantic, and if it were hollow, you could fill it with around 64.3 million Earth moons. If you could fill it with Earth-sized planets, you would need about 1.3 million Earths.

The Sun has a radius of 696.340 km / 432.685 mi and a diameter of 1.39 million km / 864.000 mi. It is 330,000 times more massive than Earth.

Did you know?

  • The largest moon in the Solar System, namely Ganymede, has a diameter of around 1.51 times that of our Moons.
  • The Moon is located at about 384,400 kilometers / 238,855 miles away from Earth, or 1.29 light-seconds.
  • The Moon is 384,400,000 meters away from us, while in inches, the Moon is 15.13 billion inches away from Earth
  • The Moon can get as far as 406,700 km / 252,711 mi away from Earth – apogee – and as close as 356,400 km / 221,456 mi away – perigee.
  • On average, it would take you around three days to get to the Moon.
  • The first human-crewed spacecraft to be sent to the Moon, the Apollo 11, arrived in just 51 hours and 49 minutes to the Moon.
  • The slowest mission, which involved a trip to the Moon, was ESA’s SMART-1. The lunar probe reached the Moon in 1 year, one month, and two weeks. This slow trip was intentional, as the probe used an ion engine as a propellant, using only 82 kg of xenon for the entire mission.
  • The Luna 1 probe traveled at around 10,500 km/hr, and it reached the Moon in just 36 hours. The probe completed a flyby of the Moon, and it was launched in 1959.
  • The Moon is 8.20 light minutes away, or 500 light-seconds away from the Sun.
  • If the Moon were to disappear, it would take us 1.29 seconds to realize this.


  1. Wikipedia
  2. NASA
  3. Space
  4. Theconversation

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