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Introduction
The planetary system we call home is located in an outer spiral arm of the Milky Way galaxy.
The planet Mars is the only terrestrial planet that has more than one moon. Deimos is the smaller of its two moons and if you look at both moons, they have a lumpy appearance of an asteroid. Phobos is one of the two moons that orbits Mars. It is only 3,700 mi/6,000 km above the surface and this is one of the main reasons that. Stars & Planets Moon Science Fair Projects Mars Science Fair Projects. High School - Grades 10-12. P=Project E=Experiment. Learn about how and why NASA false-colors x-ray images; then follow the same procedure to create your own images and compare them to the NASA ones.
Our solar system consists of our star, the Sun, and everything bound to it by gravity — the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, dwarf planets such as Pluto, dozens of moons and millions of asteroids, comets and meteoroids.
Beyond our own solar system, there are more planets than stars in night sky. So far, we have discovered thousands of planetary systems orbiting other stars in the Milky Way, with more planets being found all the time. Most of the hundreds of billions of stars in our galaxy are thought to have planets of their own, and the Milky Way is but one of perhaps 100 billion galaxies in the universe.
While our planet is in some ways a mere speck in the vast cosmos, we have a lot of company out there. It seems that we live in a universe packed with planets — a web of countless stars accompanied by families of objects, perhaps some with life of their own.
Size and Distance
Size and Distance
Our solar system extends much farther than the eight planets that orbit the Sun. The solar system also includes the Kuiper Belt that lies past Neptune's orbit. This is a sparsely occupied ring of icy bodies, almost all smaller than the most popular Kuiper Belt Object, dwarf planet Pluto.
And beyond the fringes of the Kuiper belt is the Oort Cloud. This giant spherical shell surrounds our solar system. It has never been directly observed, but its existence is predicted based on mathematical models and observations of comets that likely originate there.
The Oort Cloud is made of icy pieces of space debris the sizes of mountains and sometimes larger, orbiting our Sun as far as 1.6 light years away. This shell of material is thick, extending from 5,000 astronomical units to 100,000 astronomical units. One astronomical unit (or AU) is the distance from the Sun to Earth, or about 93 million miles (150 million kilometers). The Oort Cloud is the boundary of the Sun's gravitational influence, where orbiting objects can turn around and return closer to our Sun.
The Sun's heliosphere doesn't extend quite as far. The heliosphere is the bubble created by the solar wind—a stream of electrically charged gas blowing outward from the Sun in all directions. The boundary where the solar wind is abruptly slowed by pressure from interstellar gases is called the termination shock. This edge occurs between 80-100 astronomical units.
Two NASA spacecraft, launched in 1977, have crossed the termination shock: Voyager 1 in 2004 and Voyager 2 in 2007. But it will be many thousands of years before the two Voyagers exit the Oort Cloud.
Formation
Formation
Our solar system formed about 4.5 billion years ago from a dense cloud of interstellar gas and dust. The cloud collapsed, possibly due to the shockwave of a nearby exploding star, called a supernova. When this dust cloud collapsed, it formed a solar nebula—a spinning, swirling disk of material.
At the center, gravity pulled more and more material in. Eventually the pressure in the core was so great that hydrogen atoms began to combine and form helium, releasing a tremendous amount of energy. With that, our Sun was born, and it eventually amassed more than 99 percent of the available matter.
Matter farther out in the disk was also clumping together. These clumps smashed into one another, forming larger and larger objects. Some of them grew big enough for their gravity to shape them into spheres, becoming planets, dwarf planets and large moons. In other cases, planets did not form: the asteroid belt is made of bits and pieces of the early solar system that could never quite come together into a planet. Other smaller leftover pieces became asteroids, comets, meteoroids, and small, irregular moons.
Structure
Structure
The order and arrangement of the planets and other bodies in our solar system is due to the way the solar system formed. Nearest the Sun, only rocky material could withstand the heat when the solar system was young. For this reason, the first four planets—Mercury, Venus, Earth and Mars—are terrestrial planets. They're small with solid, rocky surfaces.
Meanwhile, materials we are used to seeing as ice, liquid or gas settled in the outer regions of the young solar system. Gravity pulled these materials together, and that is where we find gas giants Jupiter and Saturn and ice giants Uranus and Neptune.
Potential for Life
Potential for Life
Our solar system is the only place we know of that harbors life, but the farther we explore the more we find potential for life in other places. Both Jupiter’s moon Europa and Saturn’s moon Enceladus have global saltwater oceans under thick, icy shells.
Moons
Moons
There are more than 150 known moons in our solar system and several more awaiting confirmation of discovery. Of the eight planets, Mercury and Venus are the only ones with no moons. The giant planets grab the most moons. Jupiter and Saturn have long lead our solar system’s moon counts. In some ways, the swarms of moons around these worlds resemble mini versions of our solar system. Pluto, smaller than our own moon, has five moons in its orbit, including the Charon, a moon so large it makes Pluto wobble. Even tiny asteroids can have moons. In 2017, scientists found asteroid 3122 Florence had two tiny moons.
As 2019 comes to a close, it's time to review some of the biggest space science stories of the year.From a world with three suns in its sky to lots of possibly habitable real estate, the past year has seen some incredible discoveries. Here are 10 of the most memorable.Related:More: 10. Teegarden's StarThis graphic shows a comparison of the habitable zones of several alien planets, and how the Teegarden's Star planets measure up. (Image credit: C. Harman)In June 2019, researchers reported that they had circling a red dwarf known as Teegarden's Star, which lies only 12.5 light-years from Earth.The newfound worlds complete one lap around their host star in just 4.9 and 11.4 Earth days, respectively.
Despite these close orbits, they're still thought to reside in the ' — the range of distances from a star that can support the existence of liquid water on a world's surface — because Teegarden's star is so dim.From the data collected so far, scientists believe there might be more exoplanets to find in this system too. PloonetsAn artist's illustration of a potentially habitable exomoon orbiting a giant planet in a distant solar system. Such worlds could get stripped of their host planets and orbit stars independently, becoming 'ploonets.' (Image credit: NASA GSFC/Jay Friedlander and Britt Griswold)Who said space isn't adorable? In a preprint paper published on the website arXiv in July 2019, scientists gave a fanciful name to a class of wandering.
In the scenario described in the paper, these exomoons were ripped from the gravitational pull of their host planet and pulled toward their host star.No longer just a moon, but still not quite an exoplanet, these weird exomoons needed a special name. Previous research had thrown around 'moonmoon,' but the paper published in JulyPloonets are purely theoretical right now, but the paper showed how their journeys (and subsequent slow deaths) around their host stars might leave recognizable light signals. The researchers think that this light signature might explain some previously unexplained astronomical observations. Three suns!An artist's depiction of the view from a moon's surface of a gas giant and three suns.
(Image credit: NASA/JPL-Caltech)Thanks to a little help from NASA's Transiting Exoplanet Survey Satellite (TESS), scientists discovered a strange new exoplanet in a three-star system with a surface temperature around 320 degrees Fahrenheit (160 degrees Celsius.) The exoplanet, is 22.5 light-years from Earth and, despite having stars in triplicate, appears to make an orbit around one of them every five days. The other two simply loom in the exoplanet's sky.In addition to its novel setup, scientists say that the exoplanet would be a perfect candidate for future atmospheric exploration thanks to its positioning between the stars and Earth. Scientists believe this would make it possible for even ground-based Earth telescopes to make observations about the exoplanet. Gassy preteen with two sunsAn illustration of Kepler-47, an exoplanet that, like DS Tuc Ab, orbits, two suns.
(Image credit: NASA/JPL-Caltech/T. Pyle)In March 2019, scientists used TESS data to discover a that researchers believe to be a mere 43 million years old. The exoplanet, called DS Tuc Ab, orbits one star in a two-star system once every eight days.And because DS Tuc Ab is still relatively young, scientists are interested in learning more about what this world's history could tell us about the formation of planets in. For example, DS Tuc Ab still experiences considerable losses of its atmospheric gas due to radiation from its host star. Scientists hope to extrapolate this knowledge about DS Tuc Ab to imagine what might happen to Earth and other planets closer to home if they were to lose their atmospheres.Related: 6. GJ 357 d: A habitable world? In July 2019, scientists used TESS data to find yet another treasure trove of possibly habitable exoplanets.
The data in the dwarf star system GJ 357, which lies 31 light-years from Earth.Two of the planets — GJ 357 c and d — can be classified as 'super-Earths,' worlds slightly bigger than our own. Meanwhile, GJ 357 b is something called a hot Earth, meaning that, while its size might be Earth-like, its surface gets much hotter (about 490 degrees Fahrenheit, or 254 degrees Celsius) than that of our own planet.GJ 357 d in particular has grabbed a lot of attention, because it may well fall into the coveted habitable zone.
This planet completes one lap around the host star every 55 Earth days.5. A snowball's chanceAn artist's impression of a 'snowball Earth.' (Image credit: NASA)Scientists have been peering into Earth's baby book to learn a little more about a kind of exoplanet deemed a 'snowball.'
At certain points in their lives, snowballs can become tidally locked with their host star, always showing it the same face, and as a result develop huge, eyeball-like icy oceans on that face.Earth itself went through its own snowball phases as a younger planet. Because of this fact, scientists have speculated that snowball exoplanets may well be capable of sustaining life — and research suggests they might even be better at it than originally imagined.The paper focused on what might be happening on the land of these snowball planets instead of just their oceans. The study found that snowball planets would likely have relatively temperate inland zones, where temperatures hover around 50 degrees Fahrenheit (10 degrees Celsius) and above — something that Earth-like life could easily handle. Football-shaped worldThe top of WASP-121b's atmosphere is heated to a blazing 4,600 degrees Fahrenheit (2,500 Celsius), hot enough to boil some metals.
(Image credit: G. Bacon (STSci)/NASA/ESA)In August 2019, scientists reported finding a strange, shedding its atmosphere at a rapid rate — and losing heavy metals like iron and magnesium along with it. This big, puffy exoplanet, called WASP-121b, is something called a 'hot Jupiter,' and it orbits so close to its sun that its temperature is hotter than any other known planet — a whopping 4,600 degrees Fahrenheit (2,538 Celsius) in the upper atmosphere.The proximity to its star not only heats up the exoplanet but also causes its football-like bulge as the star's gravity literally threatens to tear the exoplanet apart. Scientists were able to make this original observation using NASA's Hubble Space Telescope but hope to investigate the exoplanet further using the agency's James Webb Space Telescope, which is scheduled to launch in 2021. Exoplanet water-vapor drama.