Planets, their moons, asteroids and comets in our solar system all orbit or rotate around the Sun in a circle, with some such as Mercury, Venus and Mars orbiting within its confines; Jupiter, Saturn, Uranus and Neptune orbit further out and are solid balls of rock and metal.
Astronomers still have much to learn about our solar system; other planets, like Pluto, boast active volcanoes that spew ice-spewing volcanic vents while Mars sports a canyon that covers more area than the United States! There is much for astronomers to uncover about our universe.
The Sun
The Sun is an enormous ball of hot gas that generates light and heat through nuclear fusion, acting as the center of our solar system and drawing all other bodies in to its orbit or spin around it – such as our 8 (formerly 9 planets with their combined 210 known moons, many asteroids and comets; dwarf planets like Pluto; as well as vast reaches of space dust.
The Sun’s core is home to temperatures reaching 27 million degrees Fahrenheit (15 million Celsius), where nuclear fusion takes place to transform hydrogen into helium. But most other parts of its surface – from photosphere to corona and chromosphere – remain significantly cooler with only 10,000 degrees F (5,500 C). Astronomers first discovered helium’s existence when they observed bright lines not present on Earth that did not correspond with earthbound spectrum lines; they named this new element after Helios, Greek god of sun worshipping glory and illumination.
The Sun’s gravity provides the foundation of our solar system, keeping its largest rocky planets and smaller icy objects orbiting in orbit around it. Furthermore, its gravitational pull influences interstellar space through its interaction with interstellar space’s boundary (heliopause), where most of the Sun’s ejected particles and magnetic fields dissipate into interstellar space. Furthermore, its energy impacts interstellar medium via its solar wind — an outflowing of extremely hot charged particles from its photosphere, chromosphere and corona which go from quite calm to violently active over 11 years – before blowout of solar wind into space to transport this energy across interstellar space where its energy affects particles of interstellar medium.
The Moon
The Moon stands tall in the night sky, lit up with brightly lit craters and flat areas of solidified lava known as maria. It rotates once during each lunar orbit and 12 people have set foot upon its surface; sunlight reflected from it takes approximately 1.3 seconds to reach Earth.
Today the Moon may seem peaceful and tranquil; however, its birth was anything but tranquil. Astronomers believe a Mars-sized rock smashed into Earth 4.5 billion years ago, sending shockwaves through our atmosphere which then collided into fragments that eventually coalesced to form our Moon.
Once the moon formed, its orbit began to gradually change each year until now it lies about 1.5 inches further away than when it first emerged. That may seem like a long way, but planetary scientists can still use its data to learn more about what occurred early in our Solar System’s history.
Scientists study the chemistry of Moon rocks to gain insight into the history and formation of our Solar System and how the planets came to exist. For instance, iron and magnesium can give an indication as to its composition of its rocky mantle; furthermore they can study its tectonic structures to better understand how it has developed over time.
The Solar System is comprised of more than just our Sun and 8 planets; it also houses millions of smaller objects made up of rock, metal and ice known as asteroids, meteoroids and comets that orbit both within our Solar System as well as beyond it. Scientists think most asteroids have died out but some still come back to life; asteroids play an integral part in our Solar System as well as potentially holding secrets about other worlds!
The Earth
Our Solar System is an interdependent system dominated by gravity that connects objects that orbit around our Sun. This includes eight (formerly nine) planets with over 200 moons orbiting them as well as numerous asteroids and comets; vast expanses of highly tenuous gas and dust known as interplanetary medium; as well as our home planet Earth itself.
Mars is the sole planet where life has emerged, at an ideal distance from the Sun and with just enough nitrogen and oxygen in its dense atmosphere to protect it from harmful solar radiation and keep fertile by an ongoing cycle of rock forming, colliding and breaking apart due to tectonic plates. Furthermore, Earth is unique among planets within our Solar System in having seasons; summer occurs when its Northern Hemisphere points toward Sun while winter sets in when its Southern Hemisphere points opposite direction.
Earth, like other terrestrial planets, features an iron and nickel core surrounded by solid rock mantle layers and covered by an outer mantle of solid rock with an air layer covering them both. What sets Earth apart from other terrestrial planets, however, is its unique properties as the only planet with water on its surface – oceans, rivers lakes and snow being its hallmark characteristics that scientists continue to study today. Since it formed some 4.6 billion years ago it has undergone dramatic changes and scientists continue making great strides in understanding its creation and evolution over time.
The Planets
The Solar System comprises all that orbits the Sun: planets, their moons, asteroids, comets and vast expanses of gas and dust. It is held together by its immense gravitational force; without it it would disintegrate.
Planets and their moons are round celestial bodies that revolve around the Sun like clockwork, spinning on an axis as they orbit. Each planet is covered by its own layer of gasses; Mercury’s has thin atmosphere while Venus has dense clouds of sulfuric acid – yet all are smaller than our Sun!
These cosmic bodies were formed when the slow-rotating cloud of dust and gas known as the Solar Nebula collapsed under its own weight, colliding to shape material into a flat plane. Ancient Greeks noticed five planet-like objects within this plane they named “The Seven Luminaries (or Planets), later added Pluto as it was discovered further beyond Neptune.
At present, the International Astronomical Union (IAU) recognizes eight planets within our Solar System. Mercury, Venus, Earth and Mars form what are known as terrestrial planets; Jupiter Saturn Uranus Neptune are classified as gas giants since they consist mostly of hydrogen and helium with higher proportions of water vapor, ammonia and methane; all but Pluto feature rings composed of ice dust and small rocks.
Astronomers have gained much insight into the planets through both direct and indirect observation. Astronomers use telescopes to detect light reflecting off of planet surfaces; this data helps astronomers better understand each planet’s characteristics and history.
The Dwarf Planets
The Solar System currently boasts five officially identified dwarf planets, but this number could grow. A dwarf planet is defined as any body which is large enough to assume a nearly round shape but has yet to clear out all surrounding space from its orbit. The International Astronomical Union (IAU) adopted this classification in 2006 when they demoted Pluto from being one of nine planets to an official dwarf planet alongside smaller bodies such as Eris and Ceres.
These objects resemble planets in many respects and may feature moons or rings; the key difference being that dwarf planets do not possess enough mass to have captured and accumulated most objects in their vicinity and as such have not cleared away much space from within their orbits. Furthermore, some dwarf planets feature elliptical rather than circular shapes, often linked tidally by other bodies like Pluto with Charon, or Haumea with Hi’iaka as companion bodies.
Ceres, Pluto, Makemake, Haumea and Eris are among the more notable and well-known dwarf planets located in our Solar System’s outer Kuiper belt – they all orbit around our Sun. Ceres is one of the smallest planets, comprising of rocky terrain that could contain subsurface water ice deposits; it was discovered geologically active by spacecraft as the first object discovered to have ongoing geological processes. Makemake and Haumea, two egg-shaped dwarf planets inspired by Hawaiian mythology, have both been visited by spacecraft. However, hundreds of other candidates also meet criteria for dwarf planethood including Gonggong, Orcus, Quaoar Sedna Salacia 2002 MS4 etc.