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Sheer vastness -

The solar system is, quite frankly, massive. NASA's Voyager 1 spacecraft (launched in 1977) became the first human-made object to enter interstellar space in 2012 by crossing the heliopause, which is the boundary of the solar system. It took more than three decades to travel the distance.

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Half-life -

Our solar system has been estimated to be around 4.6 billion years old, and scientists believe that it will only last another few billion before meeting catastrophe. This means we are currently living near the point of our solar system’s half-life.

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Major gap -

Shockingly, the distance between Earth and the Moon is large enough to fit all eight planets in a line. Although they vary in size (and the distance between us and the Moon also changes), the planets could all squeeze into the gap.

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Tilted -

Uranus rotates on its side, likely due to a past collision, causing it to roll around the Sun like a ball and giving it the most extreme seasons in the solar system. This tilt causes its poles to experience over two decades of continuous sunlight or darkness, which creates unpredictable weather patterns.

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Eruptive -

Jupiter’s moon Io is the most volcanically active moon in the solar system, emitting sulfur plumes up to 190 miles (306 km) high due to intense gravitational forces from Jupiter. Scientists are still trying to fully understand how the phenomena works.

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Volcanic monstrosity -

Speaking of volcanoes, Mars’ Olympus Mons is the largest volcano in the solar system, with a height of 16 miles (26 km) and width of 374 miles (602 km). In fact, it is bigger than the entire US state of Hawaii, and two and a half times the height of Mount Everest.

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Canyons and valleys -

The Valles Marineris canyon system on Mars stretches 2,500 miles (4,024 km), which is 10 times as long as Earth's Grand Canyon. Its formation is mysterious, possibly linked to volcanic activity on the opposite side of the planet, creating cracks and erosion from water and glaciers.

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A long journey -

Interestingly, it takes longer for Venus to orbit itself than it does to make an orbit around the Sun. A single day on the planet (one full rotation on its axis) takes about 243 Earth days, while its rotation around the Sun takes about 225 Earth days. This means that a day on Venus is longer than a full year.

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An extreme planet -

Venus has a scorching, high-pressure surface, and its average wind speed reaches about 224 mph (360 km/h). A potential sign of life, phosphine, was detected in Venus’ atmosphere, but follow-up studies suggest the dry atmosphere makes life unlikely.

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Water in unexpected places -

Water was once considered rare in space, but it actually exists throughout the solar system, including in craters on Mercury, Mars, and Saturn's moon Enceladus (pictured). Jupiter’s moon Europa is a prime candidate for extraterrestrial life, with a potential ocean beneath its icy crust.

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Watery worlds -

Earth is actually not the most water-rich world in the solar system. Our planet is only fifth on the list, while the rest are moons. Jupiter’s moon Ganymede is in first place, with 46% liquid water, followed by Titan, Callisto, and Europa.

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Exploration -

NASA's spacecraft, including the Voyagers, have explored all the planets and some dwarf planets in the solar system. Voyager 1 and 2, launched over 40 years ago, continue to send data from interstellar space, providing invaluable information on our outer planets.

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Unexpected geology -

Pluto is a tiny world in the distant reaches of our solar system. In 2015, NASA’s New Horizons mission flew past the dwarf planet and took pictures of its dynamic surface, revealing icy mountains that are 11,000 feet (3,300 meters) high.

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Lunar and Planetary Institute

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Put a ring on it -

Saturn’s rings are made of reflective water ice, and they are the most visually stunning in the solar system. All the planets in the outer solar system (Jupiter, Saturn, Uranus and Neptune) have ring systems, but Saturn’s is the only one not made of rock and dust.

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The search for Planet Nine -

Mathematical models suggest the existence of a large planet beyond Neptune, which scientists have dubbed Planet Nine. Some astronomers speculate it could be a small black hole, while others argue that smaller objects collectively influence the outer solar system’s behavior.

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Unexplained energy -

Even though Neptune is far from the Sun, the planet radiates more heat than it receives and experiences winds up to 1,500 mph (2,414 km/h). This energetic atmosphere puzzles scientists, who are unsure whether the heat originates from the planet’s core or gravitational forces.

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Belts -

Earth is surrounded by energy particles known as the Van Allen radiation belts, which are created when the Earth captures solar wind from the Sun. The belts actually expand and contract with solar activity, and sometimes separate from one another.

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Oversized rocks -

The asteroid belt (located roughly between the orbits of Jupiter and Mars) contains between 1.1 and 1.9 million asteroids that are each larger than 0.6 miles (one kilometer) in diameter. More than 600,000 of these have already been identified and named.

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Taller than the sky -

The highest mountain known to man is actually on an asteroid known as Vesta in the asteroid belt. It’s one of the biggest objects in the belt, with a mean diameter of 326 miles (525 km). Its mountain (pictured here at its south pole) is a whopping 14 miles (22 km) in height, which is three times taller than Everest.

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’Oumuamua -

In 2017, an elongated cigar-shaped asteroid known as ’Oumuamua passed through our solar system. The object came from interstellar space, the first of its kind to be detected. Scientists are still baffled as to where it came from.

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Big moons -

Mercury is the smallest planet in our solar system, and yet there are two non-planetary objects in the system that are actually larger: Jupiter’s moon Ganymede and Saturn’s Titan (pictured).

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Two-faced -

Saturn’s moon Iapetus has one dark and one bright hemisphere. Scientists believe the darker side absorbs more heat, which evaporates ice and leaves rock behind.

Image credit: NASA/JPL/Space Science Institute

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Methane cycle -

Saturn’s moon Titan has an active methane cycle that is similar to Earth’s water cycle. Titan’s methane lakes and ethane-filled seas form a dynamic surface and atmosphere. Future missions could explore Titan’s depths to unlock the moon's intriguing secrets.

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Strange hexagon -

Saturn’s north pole hosts a massive storm in the shape of a hexagon, which is over 18,600 miles (30,000 km) wide and 180 miles (300 km) tall.

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Rusty planet -

As strange as it may sound, Mars is basically a planet covered in rust. Earth’s neighbor has been called the Red Planet due to its distinctive coloring, which actually comes from a large amount of iron oxide. On Earth, iron oxide appears when metal begins to rust.

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Temperature difference -

Mercury, the closest planet to the Sun, has some of the biggest variations in temperature. The planet can vary from 800°F (427°C) during the day on the side that faces the Sun to -280°F (-173°C) on its night side. This is because the planet doesn’t have an atmosphere to trap heat or shield from solar rays.

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Biggest storm -

Jupiter’s Great Red Spot is actually an anticyclonic storm that has existed for more than 350 years. The storm rotates once every six days, but scientists believe that it is shrinking. The spot was once 20,000 miles (32,190 km) wide, yet it is now around 10,250 miles (16,500 km) across.

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Love and planets -

Somewhere along its surface, the dwarf planet Pluto actually features a heart-shaped region in its landscape. The area is known as Tombaugh Regio, and is composed mainly of nitrogen ice.

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Escape -

In order to escape Earth’s gravity, a spacecraft needs to travel more than 25,008 mph (40,247 km/h). This speed would put the spacecraft near Mach 33, which is 33 times the speed of sound.

Sources: (Space.com) (Astronomy Magazine) (NASA Science) (Britannica) (Big Think)

See also: Fascinating and mysterious stars of the cosmos

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