1. The solar system consists of the sun, planets, dwarf planets, moons, and numerous smaller objects such as comets and asteroids.
194 moons, 3,583 comets, and 796,289 asteroids have been found in the solar system.
2. Though it is common for most people to believe that the edge of the Solar System is that of Pluto’s orbit, this is far from the truth.
The edge of the solar system is 1,000 times farther away than Pluto.
3. The four smaller inner planets, also known as the “terrestrial planets,” are primarily composed of rock and metal.
4. The four outer planets, also known as the “gas giants,” are substantially larger and more massive than the inner planets.
5. We live inside the sun.
The sun’s outer atmosphere extends far beyond its visible surface. Our planet orbits within this tenuous atmosphere, and we see evidence of this when gusts of the solar wind generate the Northern and Southern Lights.
6. Mercury has the most extreme temperature fluctuations in the Solar System.
The temperature during the day can reach 840 degrees Fahrenheit (450 degrees Celsius), but at night, temperatures can get as low as minus 275 F (minus 170 C). The difference between both the extremes is 1100 F, which is the most extreme in our solar system.
7. Mercury is the second densest planet.
Each cubic centimeter has a density of 5.4 grams, with only the Earth having a higher density.
8. Mercury has no moons or rings.
This is because of its low gravity and lack of atmosphere.
9. Mercury is only the second hottest planet.
Venus is hotter than Mercury despite being further away from the Sun. Its mean temperature is 462°C. This is because of the high concentration of carbon dioxide in Venus’ atmosphere, which works to produce an intense greenhouse effect.
10. Venus rotates in the opposite direction to most other planets.
One possible reason for this might be a collision with an asteroid or other object.
11. Venus is the second brightest object in the night sky.
Only the Moon is brighter. Venus is so bright it can be seen during the daytime on a clear day.
12. Venus is often called the Earth’s sister planet.
Of all the solar system’s planets, Venus is the closest to a twin of Earth, with a similar size, orbit, and composition.
13. Venus is also known as the Morning Star and the Evening Star.
Early civilizations thought Venus was two different bodies. These were called Phosphorus and Hesperus by the Greeks, and Lucifer and Vesper by the Romans. This is because it was visible both before and after sunrise.
14. No man has been on the Moon in the last 48 years.
Apollo 17 took the 11th and 12th people to the Moon’s surface and marked the Apollo program’s end in 1972.
15. The Moon is moving away from us by 3.78 cm (1.48 in) a year.
While 3.78cm may not seem like much, this small difference over a long enough time could affect Earth’s life, making the planet slow down.
16. We always see the same side of the Moon.
This is because the Moon rotates around on its own axis in exactly the same time it takes to orbit the Earth, meaning the same side is always facing the Earth. The side facing away from Earth has only been seen by the human eye from spacecraft.
17. Moon was part of the Earth.
A prevailing theory is that the Moon was once part of the Earth, and was formed from a chunk that broke away due to a huge object colliding with Earth when it was relatively young.
18. Mars had water in the ancient past.
The first signs of trickling water are dark stripes or stains on the crater wall and cliffs seen in satellite images. Even now Mars has been known to have water in the form of ice
19. Mars is home to the tallest mountain in the solar system.
Olympus Mons, a shield volcano, is 21km high and 600km in diameter.
20. The planet is named after Mars, the Roman god of war.
The ancient Greeks called the planet Ares, after their god of war; the Romans then did likewise, associating the planet’s blood-red color with Mars, their own god of war.
21. Jupiter is massive
The mass of Jupiter is 318 times as massive as the Earth. Jupiter is 2.5 times more massive than all of the other planets in the Solar System combined.
22. Jupiter is the fastest spinning planet in the solar system.
For all its size and mass, Jupiter sure moves quickly. In fact, with a rotational velocity of 12.6 km/s, the planet only takes about 10 hours to complete a full rotation on its axis.
23. Jupiter has dangerous radiation surrounding it.
This rapid rotation also helps generate Jupiter’s powerful magnetic fields and contributes to its dangerous radiation.
24. The great red spot has been around for a long time.
It measures between 24,000 km in diameter and 12–14,000 km in height. As such, it is large enough to contain two or three planets the size of Earth’s diameter. And the spot has been around for at least 350 years.
25. Jupiter has rings.
Saturn is not the only planet with rings. Jupiter and Uranus also have rings but are faint.
26. When an asteroid hits the earth’s surface its called a meteorite.
Each day, more than 100 tons of material from asteroids and comets fall toward the earth. Most of it is destroyed by friction as it passes through our atmosphere. If something does hit the ground, it is known as a meteorite.
27. There is a region in space where most asteroids are situated.
It is called the asteroid belt – a region between the orbits of Mars and Jupiter.
28. An asteroid impact around 65 million years ago caused a chain reaction.
This led to the extinction of the dinosaurs and affected all life on earth, according to scientists.
29. An asteroid can have rings.
An asteroid named Chariklo was found to have rings; scientists made the surprise discovery in 2013. It had two rings, according to reports.
30. Saturn goes around the Sun very slowly.
A year on Saturn is more than 29 Earth years. Saturn spins on its axis very fast. A day on Saturn is 10 hours and 14 minutes.
31. Saturn has been visited by four spacecraft.
These are Pioneer 11, Voyager 1 and 2, and the Cassini-Huygen mission. Cassini entered into orbit in 2004 and continued to send information till 2017.
32. Saturn is the least dense planet in the solar system.
Saturn has a density of 0.687 grams/cubic centimeter. Just for comparison, water is 1 g/cm3, and the Earth is 5.52. That means the whole planet can actually float in water.
33. The day Saturday was named after Saturn.
Saturn is the Roman god of agriculture, known in Ancient Greece as Cronos. In Latin we have dies Saturni and it’s not hard to see that Saturday today is still very much Saturn’s day
34. It is very windy on Saturn.
Winds around the equator can be 1,800 kilometers per hour. On Earth, the fastest winds “only” get to about 400 kilometers per hour.
35. Uranus is known as the “sideways planet” because it rotates on its side.
The planet rotates in a retrograde direction, opposite to the way Earth and most other planets turn. Uranus rotates sideways and “rolls” around the Sun rather than “spinning” like the other planets.
36. Uranus was the first planet found using a telescope.
It is too dim to have been seen by the ancients. William Herschel tried to have his discovery named “Georgian Sidus” after King George III.
37. Uranus has 27 known moons, most of which are named after literary characters.
Uranus has 27 known moons, and they are named after characters from the works of William Shakespeare and Alexander Pope.
38. Uranus has the coldest planetary atmosphere.
Uranus’s minimum surface temperature is -224°C – making it the coldest of the eight planets.
39. Days are short, but the years are very long.
Uranus takes about 17 hours to rotate once (a Uranian day), and about 84 Earth years to complete an orbit of the Sun (a Uranian year).
40. Only one spacecraft has flown by Uranus.
In 1986, the Voyager 2 spacecraft swept past the planet at a distance of 81,500 km. It returned the first close-up images of the planet, its moons, and rings.
41. Neptune spins on its axis very rapidly.
Its equatorial clouds take 16 hours to make one rotation. This is because Neptune is not a solid body.
42. Neptune is the Coldest Planet in the Solar System.
Temperatures on Neptune can dip down to 51.7 Kelvin, or -221.45 degrees Celsius (-366.6 °F). Pluto gets colder, experiencing temperatures as low as 33 K (-240 °C/-400 °F). But then again, Pluto isn’t a planet anymore.
43. Neptune Probably Captured its Largest Moon, Triton.
Triton circles Neptune in a retrograde orbit. That’s means that it orbits the planet backward relative to Neptune’s other moons. This is seen as an indication that the moon didn’t form in a place like the rest of Neptune’s moons. Triton is locked into synchronous rotation with Neptune.
44. Neptune has been visited only once.
The only spacecraft that has ever visited Neptune was NASA’s Voyager 2 spacecraft in 1989. The interesting news is that there no plans to visit this planet any time soon. Maybe sometime in the 2030s Neptune may be revisited.
45. Pluto was reclassified from a planet to a dwarf planet in 2006.
This was when the IAU formalized the definition of a planet as “A planet is a celestial body that
- is in orbit around the Sun,
- has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
- has cleared the neighborhood around its orbit.”
46. An 11-year-old girl gave Pluto its name.
When Venetia Burney’s grandfather told her the news of the newly discovered planet, she proposed Pluto’s name, after the Roman god of the Underworld.
47. Pluto is one-third water.
Pluto’s surface is covered with ices and has several mountain ranges, light and dark regions, and a scattering of craters.
48. The term “plutoid” is used to describe objects in the solar system that are rounded and orbit the Sun beyond the orbit of Neptune.
There are currently only four recognized plutoids – Pluto, Eris, Haumea, and Makemake.
49. Disney’s Pluto, the dog, was named after the former planet.
Disney’s Pluto, the dog, debuted in the same year the former planet was discovered and was named after the former planet.
50. Pluto has a heart shape on its surface.
The heart-shaped feature is now called Tombaugh Regio. It’s a large, bright plain – largest feature on the former planet – named for Pluto’s discoverer, Clyde Tombaugh.