Aerospace Dimensions

Aerospace Dimensions Module 5 Space Environment

Contents • Chapter 1 – Space • Chapter 2 – The Solar System • Quiz • Credits

Chapter 1 Space

What is space? Space is the region beyond the immediate influence of Earth and it’s atmosphere, and is defined by the Air Force and by NASA as starting at an altitude of 50 miles. Anyone who reaches this height is awarded astronaut’s wings. Contents

Characteristics of Space One of the major characteristics of space is that there’s no atmosphere, and therein, no oxygen. Because space is also a near vacuum, there is very little molecular movement, meaning the temperature is very, very low. The temperature in space is defined as absolute zero, or the temperature at which there is zero molecular movement. The temperature is -273°C. Contents

Characteristics of Space Many people also think of space as having 0 gravity. No matter where you go in the universe, there is always gravity pulling on you, which is why we call the gravity in space, microgravity, as it is much smaller than when on the surface of a celestial body. Contents

Characteristics of Space There are three general terms used when describing distances in space: cislunar, interplanetary, and interstellar. When talking about distances it’s also important to remember that space is VERY big, about 156 billion light-years to be more precise, or, in other words, 936,000,000,000,000,000,000,000 (936 sextillion) miles across Contents

Characteristics of Space Cislunar space is defined as the region of space in between the Earth and the Moon, a distance of about 237,087 miles. Within cislunar space is most of Earth’s magnetosphere. As far as space goes, cislunar space is pretty crowded, containing man-made satellites, meteoroids and even astronauts. Contents

Characteristics of Space Interplanetary space is the next step out from cislunar space, and is the space between our Sun, and the orbit of the most distant planet, which is Neptune. Neptune’s orbit is approx. 2,799,300,000 miles from the Sun, making interplanetary space a significantly large region than cislunar space. This region contains all 8 planets, their moons, the asteroid belt, comets, as well as charged particles and magnetic fields. Contents

Characteristics of Space Interstellar space is much, much larger than interplanetary space. Interstellar space is the region in between different stars. The nearest star to our Sun is 4.56 light years away, meaning it’s 27,360,000,000,000 (27 trillion, 360 billion) miles away. Contents

Celestial Bodies There are a HUGE number of different types of celestial bodies in our universe. If you can think it up, and it’s physically possible, then somewhere in the universe, it’s almost definitely happened. Contents

Celestial Bodies One celestial body most people are familiar with is a galaxy. Galaxies are massive collections of stars and gas and are arranged in a few different forms: elliptical, spiral, and irregular. Elliptical galaxies are oval in shape, spiral galaxies have spiraling arms moving out from a bright center, and irregular galaxies have no particular shape. Contents

Celestial Bodies Another type of celestial body is a nebula. Nebulae are much smaller than galaxies, in fact, many nebulae are within galaxies. A nebula is a large cloud of gas and dust. Nebulae are very interesting as they are where stars are born at – using the dust and gas they are made up of. Many nebulae are the remnants of a dying star. Contents

Celestial Bodies Stars are also major celestial bodies in our universe, forming the hubs around which solar systems develop. Stars are bodies of very hot gasses such as hydrogen and helium. Stars are also gigantic tug-of-war games between gravity and the pressure pushing outward from within the star from the hot gasses. Contents

Celestial Bodies Another formation we use is a constellation of stars. Constellations are groupings of stars as we see them from Earth. Currently, there are 88 constellations we use today. Many are named after mythology. Many people know constellations such as Orion or Ursa Major (which contains the Big Dipper). Contents

Space Around Earth Space around Earth is very active because the atmosphere may end at approx. 50 miles, but the magnetosphere extends much farther – starting at about 215 miles above Earth. Things such as the aurora borealis and the Van Allen radiation belts are examples of what interaction with the magnetosphere causes. Contents

Space Around Earth Most people know the aurora borealis as the ‘Northern Lights.’ The lights are caused by the interaction of solar particles with our magnetosphere and can occur from anywhere between 60 to 600 miles above the surface of the Earth. Contents

Space Around Earth The area surrounding Earth is not solely for show however, the Ionosphere is a critical part of our atmosphere. The Ionosphere contains a large number of ions that protect us from solar radiation and cosmic rays from around the universe. The ionosphere also reflects radio waves back down to Earth – allowing AM radios to travel very long distances. Contents

Space Around Earth Yet another key part of the area surrounding Earth is our magnetosphere. Our magnetosphere doesn’t begin until about 215 miles above the surface, but it extends are very long distance – even further than the Moon. The magnetosphere combats a large portion of solar radiation, especially from the solar wind and solar flares. Contents

Space Around Earth The area around Earth can even be harmful to astronauts. The Van Allen radiation belts can cause severe harm to astronauts if they stay in them too long – fortunately, the shuttle orbits beneath them. The belts are caused by charged particles from the Sun becoming trapped inside the magnetosphere and bounce around. Contents

Chapter 2 The Solar System

The Sun The Sun is most important body in our solar system. It provides all of our energy here on Earth as well as being the center of our solar system. The Sun is approx. 93 million miles from Earth and has a diameter 100x bigger than Earth’s. It is about 90% hydrogen, 9% helium, as well as other minor elements. The surface is also characteristically violent and dynamic. Contents

The Sun The surface of the Sun, also known as the photosphere, is so hot (about 10,000 degrees), that it’s in a plasmatic state. Because of this fluidity and the amount of energy involved, many solar disturbances can occur such as sunspots, solar flares, or solar prominences. Sunspots are the darker, cooler areas on the Sun’s surface. It’s from these spots that the prominences and flares occur. Solar prominences are large, long-lasting energy discharges that can reach out for thousands of miles and last for months. Flares are shorter lived, but are more dangerous to us as they spring up quicker and give us less notice. Contents

The Moon Earth’s single moon orbits in an elliptical trajectory around the Earth every 27 days. The orbit goes from about 252,000 miles away to 221,000 miles away. At 2,155 miles, the Moon’s diameter is only about a fourth of Earth’s diameter. Contents

The Moon The Moon’s surface is very dry and barren, with no atmosphere and no liquid water. The surface is primarily rock covered with a fine layer of dust. There are many different types of rock on the Moon, but the two most common are Moon basalt and anorthosite. The Moon’s basalt is very similar to Earth’s, but contains different minerals. The basaltic rocks make up the dark portions of the surface. Anorthosite however, is relatively rare on Earth, being only found in Greenland. Anorthosite is what the highlands (the light areas) of the Moon are covered with. Contents

Mercury Mercury is the closest planet to the Sun, being only about 36 million miles away from it. Because of this close proximity, Mercury’s year is only 88 Earth days. Mercury also rotates very slowly on it’s axis, making it’s day very long – Mercury’s days are approximately 59 Earth days, meaning there’s less than 2 Mercurian days per year. Another result of it’s very close proximity to the Sun is it’s extreme temperatures. On the day side of Mercury, temperatures reach a scorching 800 degrees, while the night side drops down to -300 degrees. Mercury’s surface is also very resembles that of the Moon – it’s very rocky, and heavily cratered as there is no atmosphere on Mercury. Contents

Venus Venus is the planet closest to Earth and is approximately the same size as Earth. Venus is 67 million miles from the Sun and takes 225 Earth days to orbit it. The similarities with Earth end here though. Venus is an extremely hot planet, due to it’s extreme greenhouse gas effect – temperatures all around the planet are about 850 degrees. Venus’ surface cannot be seen from Earth as it is enveloped in a thick layer of clouds that rotates around the planet 4 times faster than the planet rotates – a Venusian day lasts about 243 Earth days, making it’s year shorter than it’s days. Venus’ atmosphere is comprised of 96% carbon dioxide, and 4% nitrogen, as well as small amounts of other materials. Contents

Venus It is believed that extreme volcanic activity in the past has caused these thick sulfuric clouds that cover the planet, these clouds, along with the large amount of carbon dioxide in the atmosphere, do not allow heat to escape the planet, raising the temperature to very high levels. Venus is relatively smooth, although it does have some highlands and craters. It is also very easy to see Venus right before the Sun sets at night and before it rises in the morning as it’s very bright – much brighter than any star or planet in the sky. Contents

Venus Venusian Cloud Tops Venusian Surface

Earth Earth, is the only known planet that harbors life. Our atmosphere is 78% nitrogen, 21% oxygen, and has small amounts of argon, carbon dioxide, and other gasses. The atmosphere is very key to having life on Earth as it gives us the oxygen we breathe, as well as protecting us from solar radiation. Our surface is 67% completely covered in water, with the Pacific Ocean accounting for 50% of that. There is a very wide array of terrain features as well as forms of life on our planet. Our years last 365 days and our days last 24 hours. Contents

Mars Mars is the next planet from the Sun after Earth. It’s red in color due to the dust covering the surface which is primarily composed of rust. Mars has a largely barren landscape with a very thin atmosphere composed mostly of carbon dioxide. Mars also has only about have the gravity of Earth, so massive dust storms can begin, covering much of the surface of Mars at once. Mars is renowned for it’s massive volcanoes – being the planet that has the biggest volcano (Olympus Mons). Olympus Mons is 400 miles across, and is 17 miles tall (over 3 times taller than Mt. Everest). Daytime temperatures can reach as high as 65 degrees, while nighttime temperatures drop down to as low as -130 degrees. Contents

Mars Martian days are only 37 minutes longer than Earth days, however, Martian years are nearly twice as long at 687 Earth days. Many probes have been sent to Mars, such as Viking I and II, Pathfinder, Sojourner, Mariner, and several others. Many people believe that Mars may have had life at one point – and scientific evidence does point to that. However, conditions on Mars now are not suitable for life, as it has less than 1% of the pressure and water on Earth. Contents

Jupiter Jupiter is our solar system’s largest planet – having 3 times the mass of all the other planets put together. Jupiter is about 11x larger than Earth. Jupiter’s days last only about 10 hours, and this very fast rotation causes extreme weather patterns. Jupiter is also the first of the gas giants from the Sun. Hydrogen is the most prominent gas, making up 90% of Jupiter. Helium, methane, and ammonia are also present. Jupiter’s cloud tops are extremely dynamic and have very high winds and some of the biggest storms in the solar system. The biggest storm right now is the Great Red Spot – which is about 30,000 miles long and 10,000 miles wide, making it about the size of our planet. Contents

Jupiter Jupiter also has many, many moons. Currently, there are 16 known moons, 4 of which are easily visible with only a pair of high powered binoculars. These four moons are known as the Galilean Moons as Galileo was the first to see them using his very crude telescope. These moons are very unique – one even has large numbers of active volcanoes (Io). Jupiter’s temperatures have huge differences, with it being about 60,000 degrees in it’s core, to -220 degrees on it’s cloud tops. Several probes have been launched past Jupiter, such as Pioneer and Voyager. Contents

Saturn Most of us are familiar with Saturn’s extensive ring system. Saturn is the only planet with such clearly defined rings in our solar system. The rings are made from tiny particles to particles are large as boulders. The entire system extends about 250,000 miles from the surface of the planet. There are a total of seven ring layers, the first five discovered by Galileo and the last two discovered by the Pioneer spacecraft. Saturn itself is another gas giant comprised mostly of hydrogen and helium, although not nearly as large as Jupiter. Saturn’s days also last about 10 hours but it’s years are 29 Earth years long. Like Jupiter, Saturn’s very fast rotation also causes very extreme weather conditions on Saturn’s cloud tops, with winds known to reach 1,100 miles per hour. Contents

Saturn The temperatures on Saturn are not quite as extreme however, with temperatures going up to 130 degrees during the day to as low as -330 degrees during the night. Night time temperatures approach absolute zero during the night, as Saturn is nearly 900 million miles from the Sun. Saturn also has an extensive array of moons, with 18 known moons. One moon, Titan, is very unique as it has it’s own atmosphere – something no other moon in our solar system has. Contents

Saturn Titan

Uranus Uranus is the third largest planet in our solar system and is another gas giant, like Jupiter and Saturn. It’s outer layers consist primarily of hydrogen and helium, as well as some methane, which gives it it’s blue-green color. Uranus is approximately 1.6 billion miles from the Sun – about twice as far as Saturn. Uranus takes about 84 Earth years to orbit the Sun, and rotates in 18 hours. However, Uranus’ axis is tilted to 60 degrees, meaning it’s essentially tipped over on it’s side. Because of this, daylight is determined by where it is on it’s orbit around the Sun – meaning there is about 42 years of daylight, and 42 years of night. Contents

Uranus Uranus has rings, like Saturn, however, they are very thin and are very dark, so are hard to see. Uranus also has about 15 moons. Because it is very far from the Sun, Uranus is very cold, with temperatures dropping down to about -340 degrees, nearly absolute zero. Contents

Neptune Neptune is the last gas giant in our solar system, and is the fourth largest planet. Neptune wasn’t discovered until 1846 using mathematics that showed Uranus’ orbit was being influenced by another planet. Neptune and Uranus are both very similar to each other. Neptune however, orbits 3 billion miles from the Sun – a little over twice as far as Uranus. Each of Neptune’s years lasts 165 Earth years. Neptune’s days however, are only about 19 hours. Like Uranus, Neptune’s cloud tops are made primarily of hydrogen and helium, with a little methane that gives Neptune it’s blue color. Neptune also has bright white clouds of methane ice crystal. Contents

Neptune Neptune also has a VERY faint ring system. Like the other gas giants, Neptune’s weather is very dynamic. In fact, Neptune is the windiest planet in the solar system – with wind speeds recorded at over 1,500 mph. Neptune also has several large ‘dark spots’ – similar to Jupiter’s Great Red Spot. Neptune also has the Great Dark Spot, which is a storm similar to the Great Red Spot and is also about the size of Earth. Neptune has 8 moons and on it’s largest moon, Triton, temperatures of -391 degrees have been recorded – very close to absolute zero. Contents

Neptune Triton is about ¾ the size of Earth’s moon and orbits Neptune in 5.875 Earth days. Voyager 2 also showed active geysers on Triton spewing nitrogen gas and dark dust particles several kilometers into space. Contents

Pluto *Disclaimer* Pluto was recently classified in recent years as a dwarf planet by the International Astronomic Union. For the purposes of your tests however, it is still a planet as the tests were designed before it was designated a dwarf planet. Contents

Pluto Pluto was discovered in 1930, and there is still very little known about it. It’s yellowish in color and it’s days last about 6.5 Earth days. Pluto is also the smallest of our planets, and the farthest from the Sun at 4 billion miles away. Pluto is dark, and frozen. It has a rocky core with a water and ice mantle and a surface of methane frost. Pluto also has one moon, Charon, that is half the size of Pluto. Charon’s rotational period is the same as Pluto’s so they travel in a synchronous orbit, although spinning in opposite directions. Pluto’s odd orbit around the Sun also sometimes puts it closer to the Sun than Neptune. Contents

Pluto This is what Pluto and Charon are thought to look like – even the best pictures of them show no details as they are so far away, so small, and receive such little light. Contents

Aerospace Dimensions