Space

Respond to this Friday Faithfuls challenge by writing anything about Space, or you can go with whatever else that you think fits.  Sea level is the base level for measuring elevation and depth on Earth.  Since the ocean is one continuous body of water, its surface tends to seek the same level throughout the world.  Global sea level has risen between 6 and 8 inches (15-20 cm) over the last 100 years.  As you increase in elevation, there is less air above you thus the pressure decreases.  As the pressure decreases, air molecules spread out further because there is less pressure to push them together (i.e., air expands), and the temperature decreases.  Decreased air pressure means that there is less oxygen is available for breathing.  Water takes less time to boil at increased elevations because there is less pressure, and you don’t need to apply as much heat.  An elevation higher than 8,000 feet or 1,6 miles above sea level or higher, could put you at risk for normal breathing.  Mount Everest is Earth’s highest mountain and at its summit point, it has an elevation of 8,848.86 m which is just over 29,000 feet and about 5 and a half miles up from sea level.

There are five main levels that make up the Earth’s atmosphere (Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere) and each has its own specific traits.  Each of the layers are bounded by “pauses” where the greatest changes in thermal characteristics, chemical composition, movement, and density occur.  Seasons and latitude can affect the height of the different layers of Earth’s atmosphere.  Many species of birds will fly at 2,000 to 5,000 feet or higher, but being higher up they have less gravity which means that they lose body weight, and this deprives them of energy, so they have to come down.  About 99% of the water vapor that exists in the Earth’s atmosphere is present in the Troposphere.  This is why most clouds form in this atmosphere layer.  Commercial airplanes fly in the highest level of the Troposphere around 36,000 ft (10,973 m) above the surface.  Weather balloons reach about 60,000 to 105,000 feet, just short of 20 miles and they will usually burst in the Stratosphere at altitudes between 100,000 feet and 115,000 feet.  Most of the ozone molecules are in the Stratosphere where they absorb high-energy ultraviolet (UV) light from the Sun, converting the UV energy into heat.  Unlike the Troposphere, the Stratosphere actually gets warmer the higher you go!

The Ionosphere is not a distinct layer, as it is made up of a series of regions in parts of the Mesosphere and Thermosphere where high-energy radiation from the Sun has knocked electrons loose from their parent atoms and molecules.  Meteors will usually burn up in the Mesosphere, which is around 50 miles up.  Earth ends and outer space starts at the Kármán line, some 100 kilometers (62 miles) above the planet’s surface.  An aurora or the polar lights are usually located about 60 to 75 miles above the earth in the Thermosphere, which extends up to 600 km or (375 miles) above the Earth.  Earth’s gravitational field at about 250 miles above the surface is still at 88.8 percent of its strength that it has at the surface.  The majority of satellites orbiting the Earth do so at altitudes between 160 (100 miles) and 2,000 kilometers (1242 miles) and this is referred to as low earth orbit.  The outermost layer of our atmosphere is called the Exosphere and it extends from about 600 km (375 miles) to 10,000 km (6,200 miles) above the earth.  In this layer, atoms and molecules escape into space and satellites orbit the earth.  The Exosphere gradually fades away into the realm of interplanetary space and it ends about halfway to the Moon.  Where our atmosphere merges into outer space, there is a cloud of hydrogen atoms called the geocorona, which some scientists consider to be part of the Exosphere.  This outermost part of our planet’s atmosphere extends well beyond the lunar orbit, extending almost twice the distance to the Moon.  Between Earth and the Moon lies the Van Allen Belt, a zone of energetic charged particles, most of which originate from the solar wind and this does not contain any asteroids, or even rocks, but it is a zone of higher radiation that has been trapped by the Earth’s magnetosphere.

Deep space is the region of space beyond the dark side of our Moon, including Lagrange 2, or L2, (274,000 miles from Earth) the point where the gravitational influences of the Earth and Sun balance the centripetal force of a small object orbiting with them and this is also where asteroids are located.  The record for the farthest distance that humans have traveled goes to the all-American crew of famous Apollo 13 who were 400,171 kilometers (248,655 miles) away from Earth on April 14, 1970.  This record has stood untouched for over 50 years.  The moon is 384472 kilometers (238,900 miles) from earth and the James Webb Space Telescope which is located at L2 is 1.5 million kilometers (1 million miles) away from the Earth.  Luna isn’t the real name of our moon, just as Terra is not the correct name for our planet and Sol is not the name for our star.  After the moon, in one direction there is Venus and Mars is on the opposite side of the Sun.  Because of the elliptical orbits, on average Mercury is the closest planet to Earth.  In fact, during a 10,000-year span, Mercury was closest to Earth about 46.5% of the time.  Venus was the closest planet 36.3% of the time and Mars was closest 17.2% of the time.  The moons of Mars, Phobos and Deimos could be in between the Earth and Mars depending on their orbits, and Mercury and Venus don’t have moons.  Cosmic dust is everywhere in space and small volumes of hydrogen gas and helium gas, can also be found just about anywhere in space.

Rogue comets and asteroids can also be found almost anywhere in space, but most of this ancient space rubble exists between Mars and Jupiter within the main asteroid belt.  The belt is estimated to contain between 1.1 and 1.9 million asteroids larger than 1 kilometer (0.6 miles) in diameter, and millions of smaller ones.  The four largest objects, Ceres, Vesta, Pallas, and Hygiea, contain an estimated 62% of the belt’s total mass, with 39% accounted for by Ceres alone.  Ceres is a dwarf planet and it’s the only dwarf planet located in the inner solar system.  Ceres is 1/13 the radius of Earth and it has water, which is something that a lot of other planets don’t have.  Ceres takes 4.6 Earth years, to make one trip around the Sun, completing one rotation every 9 hours, making its day length one of the shortest in the solar system.

Space is very, very cold.  The baseline temperature of outer space is 2.7 Kelvins, or minus 454.81 degrees Fahrenheit, or minus 270.45 degrees Celsius, meaning that it is barely above absolute zero, the point at which molecular motion stops.  However, this temperature is not constant throughout the solar system.  The four gas giants in our solar system Jupiter, Neptune, Uranus, and Saturn are also called the Jovian planets.  Beyond them lies the Kuiper belt where the dwarf planet Pluto is located, which is 3.2 billion miles away.  The Kuiper Belt is an elliptical plane in space spanning from 30 to 55 times Earth’s distance from the sun, 4.5 to 7.4 billion kilometers or (2.5 to 4.5 billion miles).  The Oort Cloud is located at the distant edges of the Kuiper Belt between about 2,000 and 100,000 astronomical units (AU) from the Sun.  Interstellar space is the medium where matter and radiation exist between the star systems in a galaxy.  Scientists define the beginning of interstellar space as the place where the Sun’s constant flow of material and magnetic field stop affecting its surroundings.  The Voyager spacecraft have travelled further than any other space probe.  Voyager 1 and Voyager 2 left Earth in 1977.  It will take them about 300 years to reach the inner edge of the Oort Cloud.  It could take 30,000 years to fly past it!

Gravity doesn’t end, as it does not have a limit, so there is no edge of gravity.  Gravity extends forever, although it does get weaker as the distance increases, so if you wanted to reach a point where Earth’s gravity no longer has a hold on you, you’d have to fly out about 21 million kilometers, or (13 million miles).  Voyager 1 is currently 23.3 billion kilometers (14.5 billion miles) away from Earth.