Excited about exoplanets? Let’s take a tour of our own Solar System.
After this week’s NASA announcement regarding the discovery of exoplanets orbiting the TRAPPIST-1 star system, I would like to give you a tour of our cosmic neck of the woods before we look out beyond where we could currently travel to with today’s technology.
Before we get into the specific places, first we have to understand the sheer scale of our Solar System. Here are a graphic, video, and to scale info to help wrap your tiny monkey brain around the mind numbing distances involved in traversing our stellar neighborhood.
“We measure distances in our solar system by Astronomical Units (AU). One AU is equal to the distance between the sun and the Earth, which is about 93 million miles (150 million km).”
Solar System Quick Facts:
- Planets 8 (You can stand on 4[Rocky], you can’t stand on 4 [Gas & Ice])
- Dwarf Planets: 5
- Moons: Known = 149 | Provisional = 24 | Total = 173
- Comets: More than 3,400
- Asteroids: More than 715,000
- Age: Our solar system formed about 4.6 billion years ago
- Location: Milky Way Galaxy
- Speed: Our solar system is moving with an average velocity of 450,000 miles per hour (720,000 kilometers per hour). But even at this speed, it takes us about 230 million years to make one complete orbit around the Milky Way.
THE SUN
- The sun makes up 99.86% of all mass in the solar system. — 332,946 Earths match the mass of the sun. The sun’s volume would need 1.3 million Earths to fill it.
- The sun, like others stars, is a ball of gas. In terms of the number of atoms, it is made of 91.0% hydrogen and 8.9% helium. By mass, the sun is about 70.6% hydrogen and 27.4% helium.
- At the core, the temperature is about 27 million degrees Fahrenheit (15 million degrees Celsius), which is sufficient to sustain thermonuclear fusion. This is a process in which atoms combine to form larger atoms and in the process release staggering amounts of energy. Specifically, in the sun’s core, hydrogen atoms fuse to make helium.
- Watch 3 years of the sun in 3 minutes.
MERCURY
- Mercury moves so fast that Einstein’s theory of relativity is required to accurately predict its orbit.
- Temperatures on Mercury’s surface can reach 800 degrees Fahrenheit (430 degrees Celsius). Because the planet has no atmosphere to retain that heat, nighttime temperatures on the surface can drop to -290 degrees Fahrenheit (-180 degrees Celsius).
- Mercury speeds around the sun every 88 days, traveling through space at nearly 50 km (31 miles) per second, faster than any other planet. One Mercury solar day (one day-night cycle) equals 175.97 Earth days.
VENUS
- Venus is roughly the same size as Earth, just slightly smaller.
- Venus’ thick atmosphere traps heat in a runaway greenhouse effect, making it the hottest planet in our solar system with surface temperatures hot enough to melt lead.
- At the level where the clouds are, about 30 miles up from the surface, it’s about the same temperature as on the surface of the Earth. NASA has an idea of how we humans could explore Venus in the near future with HAVOC.
- Relative to other plants, Venus rotates opposite and is nearly upside down
EARTH & The Moon
- Earth is the biggest of the terrestrial planets, and the fifth largest planet overall. Earth is the only planet that has a single moon.
- Earth’s global ocean, which covers nearly 70 percent of the planet’s surface, has an average depth of about 2.5 miles (4 kilometers) and contains 97 percent of Earth’s water.
- Near the surface, Earth has an atmosphere that consists of 78 percent nitrogen, 21 percent oxygen, and 1 percent other gases such as argon, carbon dioxide and neon.
- The moon is farther away from Earth than most people realize. The moon is an average of 238,855 miles (384,400 kilometers) away. That means 30 Earth-sized planets could fit in between Earth and the moon.
- When Earth was a young planet, a large chunk of rock smashed into it, displacing a portion of Earth’s interior.
MARS
- No planet has taller mountains or wider canyons. Mars has the largest volcano in the solar system, Olympus Mons, as well as a spectacular equatorial canyon system, Valles Marineris.
- There are 7 robots on Mars, two of which (Opportunity & Curiosity) are still functioning.
- Mars has two small moons, Phobos and Deimos, that may be captured asteroids. Potato-shaped, they have too little mass for gravity to make them spherical.
- Nation states such as China & The USA have plans to send humans to Mars in the near future. Along with private companies such as Space X.
- The Curiosity rover took the below picture of Earth from the surface of Mars.
ASTEROIDS
Most of this ancient space rubble can be found orbiting the sun between Mars and Jupiter within the main asteroid belt. Asteroids range in size from Vesta — the largest at about 329 miles (530 kilometers) in diameter — to bodies that are less than 33 feet (10 meters) across. . The total mass of all the asteroids combined is less than that of Earth’s Moon.
Main asteroid belt: The majority of known asteroids orbit within the asteroid belt between Mars and Jupiter, generally with not very elongated orbits.
Trojans: These asteroids share an orbit with a larger planet, but do not collide with it because they gather around two special places in the orbit (called the L4 and L5 Lagrangian points). There, the gravitational pull from the sun and the planet are balanced by a trojan’s tendency to otherwise fly out of the orbit.
Near-Earth asteroids: These objects have orbits that pass close by that of Earth. Asteroids that actually cross Earth’s orbital path are known as Earth-crossers.
Potentially Hazardous Asteroids: Stray asteroids and asteroid fragments slammed into Earth and the other planets in the past, playing a major role in altering the geological history of the planets and in the evolution of life on Earth.
JUPITER
- The planet of “mosts”: most mass, most volume, most moons (63). 88 times bigger and it would have been a star.
- The atmosphere is mostly hydrogen and helium, and its iconic Great Red Spot is a giant storm bigger than Earth that has raged for hundreds of years.
- Jupiter has the shortest day in the solar system. One day on Jupiter takes only about 10 hours (the time it takes for Jupiter to rotate or spin around once), and Jupiter makes a complete orbit around the sun (a year in Jovian time) in about 12 Earth years (4,333 Earth days).
- Jupiter’s 4 largest moon’s are some of the most interesting locations in the solar system. Io is the most volcanic-ally active body in the solar system. Ganymede is the largest moon in the solar system (even bigger than the planet Mercury). Callisto’s very few small craters indicate a small degree of current surface activity. A liquid-water ocean with the ingredients for life may lie beneath the frozen crust of Europa, making it a tempting place to explore. (NASA has recently green-lit a mission to Europa.)
- The Juno spacecraft, which successfully entered the orbit of Jupiter on July 4, 2016, will for the first time peer below the dense cover of clouds to answer questions about the gas giant and the origins of our solar system.
- Juno’s primary goal is to reveal the story of Jupiter’s formation and evolution. Using long-proven technologies on a spinning spacecraft placed in an elliptical polar orbit, Juno will observe Jupiter’s gravity and magnetic fields, atmospheric dynamics and composition, and evolution.
- Below is a photo taken of Jupiter’s south pole from the Juno spacecraft.
SATURN
- The farthest planet from Earth observable by the unaided human eye.
- Saturn’s rings are believed to be pieces of comets, asteroids or shattered moons that broke up before they reached the planet, torn apart by Saturn’s powerful gravity. They are made of billions of small chunks of ice and rock. The ring particles mostly range from tiny, dust-sized icy grains to chunks as big as a house, though a few particles are as large as mountains.
- It’s hard to imagine, but Saturn is the only planet in our solar system that is less dense than water. The giant gas planet could float in a bathtub — if such a colossal thing existed.
- The sixth planet from the sun takes 29 Earth years, or 10,756 Earth days, to complete one revolution around the sun.
- The below photo is from the Cassini spacecraft taken while orbiting Saturn. The bright orb on the right hand side and in the middle of the photo is Earth!
URANUS
- Only one spacecraft has ever visited Neptune, which spins on its side.
- This unique tilt causes the most extreme seasons in the solar system. For nearly a quarter of each Uranian year, the sun shines directly over each pole, plunging the other half of the planet into a 21-year-long, dark winter.
- One day on Uranus takes about 17 hours (the time it takes for Uranus to rotate or spin once). And Uranus makes a complete orbit around the sun (a year in Uranian time) in about 84 Earth years (30,687 Earth days).
- The first planet found with the aid of a telescope, Uranus was discovered in 1781 by astronomer William Herschel, although he originally thought it was either a comet or a star.
- Most (80 percent or more) of the planet’s mass is made up of a hot dense fluid of “icy” materials — water, methane and ammonia — above a small rocky core. Near the core, it heats up to 9,000 degrees Fahrenheit (4,982 degrees Celsius).
NEPTUNE
- The ice giant Neptune was the first planet located through mathematical predictions rather than through regular observations of the sky. Neptune was predicted by John Couch Adams and Urbain Le Verrier. The men independently accounted for the irregularities in the motion of Uranus by correctly predicting the orbital elements of a trans-Uranian planet. Using the predicted parameters of Le Verrier (Adams never published his predictions), Johann Galle discovered the planet in 1846.
- The magnetic field of Neptune is about 27 times more powerful than that of Earth.
- Despite its great distance and low energy input from the Sun, Neptune’s winds can be three times stronger than Jupiter’s and nine times stronger than Earth’s.
- Triton, Neptune’s largest moon, orbits the planet in the opposite direction compared with the rest of the moons, suggesting that it may have been captured by Neptune in the distant past.
PLUTO & DWARF PLANETS
There may be dozens of dwarf planets in our solar system. So far, we’ve classified just a handful: Pluto, Ceres, Eris, Haumea and Makemake.
Dwarf planets are a lot like regular planets:
- They both have enough mass and gravity to be nearly round — unlike odd-shaped asteroids.
- They both travel through space in a path around the sun.
The big difference?
- A dwarf planet’s path around the sun is full of other objects like asteroids and comets.
- A regular planet has a clear path around the sun. Most of the major impacts with other objects in its orbit happened billions of years ago. There is not much left over to get in the way.
Comets
We now know that comets are leftovers from the dawn of our solar system around 4.6 billion years ago, and consist mostly of ice coated with dark organic material. They have been referred to as “dirty snowballs.” They may yield important clues about the formation of our solar system. Comets may have brought water and organic compounds, the building blocks of life, to the early Earth and other parts of the solar system.
KUIPER BELT & OORT CLOUD
- Sometimes called the Edgeworth–Kuiper belt, is a circumstellar disc in the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun.[2] It is similar to the asteroid belt, but it is far larger — 20 times as wide and 20 to 200 times as massive.[3][4] Like the asteroid belt, it consists mainly of small bodies, or remnants from the Solar System’s formation. Although many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed “ices”), such as methane, ammonia and water.
- The Kuiper belt should not be confused with the theorized Oort cloud, which is a thousand times more distant and is mostly spherical. The objects within the Kuiper belt, together with the members of the scattered disc and any potential Hills cloud or Oort cloud objects, are collectively referred to as trans-Neptunian objects (TNOs).
- The Oort Cloud is believed to be a thick bubble of icy debris that surrounds our solar system. This distant cloud may extend a third of the way from our sun to the next star — between 5,000 and 100,000 astronomical units. Earth is about one astronomical unit from the sun (roughly 93 million miles or 150 million kilometers).
Beyond our solar system
- Our sun is one of at least 100 billion stars in the Milky Way, a spiral galaxy about 100,000 light years across.
- All of the stars in the Milky Way orbit a supermassive black hole at the galaxy’s center, which is estimated to be some 4 million times as massive as our sun.
- The Milky Way is part of the Local Group, a neighborhood about 10 million light years across, consisting of more than 30 galaxies that are gravitationally bound to each other.
With the news of the Trappist-1 system now having 7 planets orbiting it’s star — it is cause for scientific celebration. However, I must remind everyone: we are very, very far from reaching it anytime soon.
In the words of Carl Sagan in the video(s) below — “Earth is where we make our stand.” But that also should not stop us from exploring our own cosmic backyard and eventually BEYOND it!
“Maybe it’s a little early.
Maybe the time is not quite yet.
But those other worlds,
promising untold opportunities, beckon.
Silently, they orbit the Sun…
waiting.”
SHOT:
CHASER:
Bibliography: All photos, graphics, videos are attributed to their rightful owners. Most text was taken directly from NASA websites & Wikipedia.
