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Space Exploration Earth
Voyage into space.

Science

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Solar Cycle

The sun may be 93 million miles (149 million kilometers) away from Earth, but commotions on our nearest star have consequences much closer to home, which is why scientists have a keen interest in studying changes in the sun's activity.

The sun's temper varies on an 11-year cycle, typically taking about 5 1/2 years to move from the quieter period of solar minimum, to the more turbulent solar maximum.

 

One of the ways solar physicists monitor the solar cycle is by studying the surface of the sun for dark splotches called sunspots. These short-lived patches are caused by intense magnetic activity and tend to cluster in bands at mid-latitudes above and below the equator. The frequency and number of these mysterious dark spots on the solar surface act as indicators of the sun's activity as it moves between solar minimum and maximum. 

 

Sunspots sometimes erupt into powerful solar storms that shoot streams of charged particles into space, occasionally in the direction of Earth. Some powerful solar storms can bombard Earth's magnetic field and disrupt power grids or knock out satellites in orbit around the planet.

 

As the sun reaches the end of a cycle, new sunspots appear near the equator, and a new cycle begins with the production of sunspots at higher latitudes on the surface of the sun.

 

The Solar Bodies

Our solar system consists of an average star we call the Sun, the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. It includes: the satellites of the planets; numerous comets,asteroids, and meteoroids; and the interplanetary medium. The Sun is the richest source of electromagnetic energy (mostly in the form of heat and light) in the solar system. The Sun's nearest known stellar neighbor is a red dwarf star called Proxima Centauri, at a distance of 4.3 light years away.

 

The whole solar system, together with the local stars visible on a clear night, orbits the center of our home galaxy, a spiral disk of 200 billion stars we call the Milky Way. The Milky Way has two small galaxies orbiting it nearby, which are visible from the southern hemisphere. They are called the Large Magellanic Cloud and the Small Magellanic Cloud. The nearest large galaxy is the Andromeda Galaxy. It is a spiral galaxy like the Milky Way but is 4 times as massive and is 2 million light years away. Our galaxy, one of billions of galaxies known, is traveling through intergalactic space.

The planets, most of the satellites of the planets and the asteroids revolve around the Sun in the same direction, in nearly circular orbits. When looking down from above the Sun's north pole, the planets orbit in a counter-clockwise direction. The planets orbit the Sun in or near the same plane, called theecliptic. Pluto is a special case in that its orbit is the most highly inclined (18 degrees) and the most highly elliptical of all the planets. Because of this, for part of its orbit, Pluto is closer to the Sun than isNeptune. The axis of rotation for most of the planets is nearly perpendicular to the ecliptic. The exceptions are Uranus and Pluto, which are tipped on their sides.

 

Interplanetary Space

 

Nearly all the solar system by volume appears to be an empty void. Far from being nothingness, this vacuum of "space" comprises the interplanetary medium. It includes various forms of energy and at least two material components: interplanetary dust and interplanetary gas. Interplanetary dust consists of microscopic solid particles. Interplanetary gas is a tenuous flow of gas and charged particles, mostly protons and electrons -- plasma -- which stream from the Sun, called the solar wind.

 

The Milky Way Galaxy 

 

The Miky Way is the galaxy that contains our Solar System.  Its name "milky" is derived from its appearance as a dim glowing band arching across the night sky whose individual stars cannot be distinguished by the naked eye.  Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomersHarlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies—now known to number in the billions. The Milky Way is a barred spiral galaxy that has a diameter usually considered to be roughly 100,000–120,000 light-years but may be 150,000–180,000 light-years.  The Milky Way is estimated to contain 100–400 billion stars, although this number may be as high as one trillion. There are probably at least 100 billion planets in the Milky Way.The Solar System is located within the disk, about 27,000 light-years from the Galactic Center, on the inner edge of one of the spiral-shaped concentrations of gas and dust called the Orion Arm. The stars in the inner ≈10,000 light-years form a bulge and one or more bars that radiate from the bulge. The very center is marked by an intense radio source, named Sagittarius A*, which is likely to be a supermassive black hole. 

Andromeda Galaxy

The Andromeda galaxy, our Milky Way's closest neighbor, is the most distant object in the sky that you can see with your unaided eye — but only on a clear night from a location with a very dark sky. The galaxy is abeautiful sprial, but one fact you may not be aware of: We’re safe for a few billion years, but Andromeda is headed our way and on a collision course with the Milky Way. Here we explain that cosmic train wreck, plus explain Andromeda's location, shape and other facts.

 

Location, location, location

 

This mosaic of M31 merges 330 individual images taken by the Ultraviolet/Optical Telescope aboard NASA's Swift spacecraft. It is the highest-resolution image of the galaxy ever recorded in the ultraviolet. The image shows a region 200,000 light-years wide and 100,000 light-years high (100 arcminutes by 50 arcminutes).
Credit: NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)

View full size image

 

Located just to the north of the constellation bearing its name, the Andromeda galaxy appears as a long, hazy patch in the sky. It should appear as a smudge in the sky, even with moderate light pollution. If you live in a more populated place, you may have more trouble. Binoculars will clearly reveal its shape. [How to Find Andromeda]

 

The visible fuzzy patch of stars stretches about as long as the width of the full moon, and half as wide; only with significant magnification can you tell it stretches six times that length in fullness.

 

A spiral galaxy like the Milky Way, Andromeda contains a concentrated bulge of matter in the middle, surrounded by a disk of gas, dust, and stars 260,000 light-years long, more than 2.5 times as long as the Milky Way. Though Andromeda contains approximately a trillion stars to the quarter to half a billion in the Milky Way, our galaxy is actually more massive, because it is thought to contain more dark matter. 

 

Amazingly, this stretch of stars, which in our sky appears about as long as the full moon and half as wide, lies 2.5 million light-years away, further than any star you can see with your eyes. Also known as M31, it is the closest galaxy to the Milky Way - and it's movingcloser every day.

Collision course

 

 

Andromeda's proximity will be deadly to our galaxy. The two galaxies are rushing closer to one another at about 70 miles per second (112 kilometers per second). Astronomers estimate that it will collide with the Milky Way in about 5 billion years. By that time, the sun will have swollen into a red giant and swallowed up the terrestrial planets, so Earth will have other things to worry about.

Quantum Technology for Interstellar space travel

The Andromeda galaxy, our Milky Way's closest neighbor, is the most distant object in the sky that you can see with your unaided eye — but only on a clear night from a location with a very dark sky. The galaxy is abeautiful sprial, but one fact you may not be aware of: We’re safe for a few billion years, but Andromeda is headed our way and on a collision course with the Milky Way. Here we explain that cosmic train wreck, plus explain Andromeda's location, shape and other facts.

 

 

The space between stars is known as interstellar space, and so the space between galaxies is called intergalactic space. These are the vast empty spaces that sit between galaxies. For example, if you wanted to travel from the Milky Way to the Andromeda galaxy, you would need to cross 2.5 million light-years of intergalactic space.

 

Intergalactic space is as close as you can get to an absolute vacuum. There’s very little dust and debris, and scientists have calculated that there’s probably only one hydrogen atom per cubic meter. The density of material is higher near galaxies, and lower in the midpoint between galaxies.

Galaxies are connected by a rarefied plasma that is thought to posses a cosmic filamentary structure, which is slightly denser than the average density of the Universe. This material is known as the intergalactic medium, and it’s mostly made up of ionized hydrogen. Astronomers think that the intergalactic medium is about 10 to 100 times denser than the average density of the Universe.

 

This intergalactic medium can actually be seen by our telescopes here on Earth because it’s heated up to tens of thousands, or even millions of degrees. This is hot enough for electrons to escape from hydrogen nuclei during collisions. We can detect the energy released from these collisions in the X-ray spectrum. NASA’s Chandra X-Ray Observatory – a space telescope designed to search for X-rays – has detected vast clouds of hot intergalactic medium in regions where galaxies are colliding together in clusters.

Interstellar Space Flight
Interstellar and
Intergalactic Space Travel 

A Brief History of Space Exploration

 

Humans have dreamed about spaceflight since antiquity. The Chinese used rockets for ceremonial and military purposes centuries ago, but only in the latter half of the 20th century were rockets developed that were powerful enough to overcome the force of gravity to reach orbital velocities that could open space to human exploration.

 

As often happens in science, the earliest practical work on rocket engines designed for spaceflight occurred simultaneously during the early 20th century in three countries by three key scientists: in Russia, by Konstantin Tsiolkovski; in the United States, by Robert Goddard; and in Germany, by Hermann Oberth.

In the 1930s and 1940s Nazi Germany saw the possibilities of using long-distance rockets as weapons. Late in World War II, London was attacked by 200-mile-range V-2 missiles, which arched 60 miles high over the English Channel at more than 3,500 miles per hour.

 

After World War II, the United States and the Soviet Union created their own missile programs. On October 4, 1957, the Soviets launched the first artificial satellite, Sputnik 1, into space. Four years later on April 12, 1961, Russian Lt. Yuri Gagarin became the first human to orbit Earth in Vostok 1. His flight lasted 108 minutes, and Gagarin reached an altitude of 327 kilometers (about 202 miles).

 

The first U.S. satellite, Explorer 1, went into orbit on January 31, 1958. In 1961 Alan Shepard became the first American to fly into space. On February 20, 1962, John Glenn’s historic flight made him the first American to orbit Earth.

“Landing a man on the moon and returning him safely to Earth within a decade” was a national goal set by President John F. Kennedy in 1961. On July 20, 1969, Astronaut Neil Armstrong took “a giant step for mankind” as he stepped onto the moon. Six Apollo missions were made to explore the moon between 1969 and 1972.

 

During the 1960s unmanned spacecraft photographed and probed the moon before astronauts ever landed. By the early 1970s orbiting communications and navigation satellites were in everyday use, and the Mariner spacecraft was orbiting and mapping the surface of Mars. By the end of the decade, the Voyager spacecraft had sent back detailed images of Jupiter and Saturn, their rings, and their moons.

 

Skylab, America’s first space station, was a human-spaceflight highlight of the 1970s, as was the Apollo Soyuz Test Project, the world’s first internationally crewed (American and Russian) space mission.

 

In the 1980s satellite communications expanded to carry television programs, and people were able to pick up the satellite signals on their home dish antennas. Satellites discovered an ozone hole over Antarctica, pinpointed forest fires, and gave us photographs of the nuclear power-plant disaster at Chernobyl in 1986. Astronomical satellites found new stars and gave us a new view of the center of our galaxy.

 

Space Shuttle

 

In April 1981 the launch of the space shuttle Columbia ushered in a period of reliance on the reusable shuttle for most civilian and military space missions. Twenty-four successful shuttle launches fulfilled many scientific and military requirements until January 1986, when the shuttle Challenger exploded after launch, killing its crew of seven.

The Challenger tragedy led to a reevaluation of America’s space program. The new goal was to make certain a suitable launch system was available when satellites were scheduled to fly. Today this is accomplished by having more than one launch method and launch facility available and by designing satellite systems to be compatible with more than one launch system.

 

The Gulf War proved the value of satellites in modern conflicts. During this war allied forces were able to use their control of the “high ground” of space to achieve a decisive advantage. Satellites were used to provide information on enemy troop formations and movements, early warning of enemy missile attacks, and precise navigation in the featureless desert terrain. The advantages of satellites allowed the coalition forces to quickly bring the war to a conclusion, saving many lives.

 

Space systems will continue to become more and more integral to homeland defense, weather surveillance, communication, navigation, imaging, and remote sensing for chemicals, fires and other disasters.

History of Space Exploration and Aerodynamics

AURORAE

 

Aurorae are caused by high-energy waves that travel along a planet's magnetic poles, where they excite atmospheric gases and cause them to glow. Photons in this high-energy radiation bump into atoms of gases in the atmosphere causing electrons in the atoms to excite, or move to the atom's upper shells. When the electrons move back down to a lower shell, the energy is released as light, and the atom returns to a relaxed state. The color of this light can reveal what type of atom was excited. Green light indicates oxygen at lower altitudes. Red light can be from oxygen molecules at a higher altitude or from nitrogen. On Earth, aurorae around the north pole are called the Northern Lights.

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