User talk:The Space Lover

The Big Bang Theory
The Big Bang theory is the prevailing cosmological model explaining the existence of the observable universe from the earliest known periods through its subsequent large-scale evolution.[1][2][3] The model describes how the universe expanded from an initial state of high density and temperature,[4] and offers a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background (CMB) radiation, and large-scale structure.

Crucially, the theory is compatible with Hubble–Lemaître law — the observation that the farther away galaxies are, the faster they are moving away from Earth. Extrapolating this cosmic expansion backwards in time using the known laws of physics, the theory describes an increasingly concentrated cosmos preceded by a singularity in which space and time lose meaning (typically named "the Big Bang singularity").[5] Detailed measurements of the expansion rate of the universe place the Big Bang singularity at around 13.8 billion years ago, which is thus considered the age of the universe.[6]

After its initial expansion, an event that is by itself often called "the Big Bang", the universe cooled sufficiently to allow the formation of subatomic particles, and later atoms. Giant clouds of these primordial elements – mostly hydrogen, with some helium and lithium – later coalesced through gravity, forming early stars and galaxies, the descendants of which are visible today. Besides these primordial building materials, astronomers observe the gravitational effects of an unknown dark matter surrounding galaxies. Most of the gravitational potential in the universe seems to be in this form, and the Big Bang theory and various observations indicate that this excess gravitational potential is not created by baryonic matter, such as normal atoms. Measurements of the redshifts of supernovae indicate that the expansion of the universe is accelerating, an observation attributed to dark energy's existence.[7]

Georges Lemaître first noted in 1927 that an expanding universe could be traced back in time to an originating single point, which he called the "primeval atom". Edwin Hubble confirmed through analysis of galactic redshifts in 1929 that galaxies are indeed drifting apart; this is important observational evidence for an expanding universe. For several decades, the scientific community was divided between supporters of the Big Bang and the rival steady-state model which both offered explanations for the observed expansion, but the steady-state model stipulated an eternal universe in contrast to the Big Bang's finite age. In 1964, the CMB was discovered, which convinced many cosmologists that the steady-state theory was falsified,[8] since, unlike the steady-state theory, the hot Big Bang predicted a uniform background radiation throughout the universe caused by the high temperatures and densities in the distant past. A wide range of empirical evidence strongly favors the Big Bang, which is now essentially universally accepted.[9] The Space Lover (talk) 05:23, 22 June 2021 (UTC)

Our Solar System
The Solar System[b] is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly.[c] Of the objects that orbit the Sun directly, the largest are the eight planets,[d] with the remainder being smaller objects, the dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the natural satellites—two are larger than the smallest planet, Mercury.[e]

Solar System A representative image of the Solar System with sizes, but not distances, to scale The Sun and planets (distances not to scale) Age 4.568 billion years Location Local Interstellar Cloud, Local Bubble, Orion–Cygnus Arm, Milky Way System mass 1.0014 Solar masses Nearest star Proxima Centauri (4.25 ly) Alpha Centauri (4.37 ly) Nearest known planetary system Proxima Centauri system (4.25 ly) Planetary system Semi-major axis of outer known planet (Neptune) 30.10 AU (4.5 bill. km; 2.8 bill. mi) Distance to Kuiper cliff 50 AU Populations Stars 1 (Sun) Known planets 8 (MercuryVenusEarthMarsJupiterSaturnUranusNeptune) Known dwarf planets 2 universally accepted (PlutoEris) 1 more likely to be (Ceres) 2 more possible to be (HaumeaMakemake) Known natural satellites 575 (185 planetary390 minor planetary)[1][2] Known minor planets 796,354[a][3] Known comets 4,143[a][3] Identified rounded satellites 19 (5–6 likely in hydrostatic equilibrium) Orbit about Galactic Center Invariable-to-galactic plane inclination 60.19° (ecliptic) Distance to Galactic Center 27,000 ± 1,000 ly Orbital speed 220 km/s; 136 mps Orbital period 225–250 myr Star-related properties Spectral type G2V Frost line ≈5 AU[4] Distance to heliopause ≈120 AU Hill sphere radius ≈1–3 ly The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system's mass is in the Sun, with the majority of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials. The two largest planets, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.

The Solar System also contains smaller objects.[f] The asteroid belt, which lies between the orbits of Mars and Jupiter, mostly contains objects composed, like the terrestrial planets, of rock and metal. Beyond Neptune's orbit lie the Kuiper belt and scattered disc, which are populations of trans-Neptunian objects composed mostly of ices, and beyond them a newly discovered population of sednoids. Within these populations, some objects are large enough to have rounded under their own gravity, though there is considerable debate as to how many there will prove to be.[9][10] Such objects are categorized as dwarf planets. The only certain dwarf planet is Pluto, with another trans-Neptunian object, Eris, expected to be, and the asteroid Ceres at least close to being a dwarf planet.[f] In addition to these two regions, various other small-body populations, including comets, centaurs and interplanetary dust clouds, freely travel between regions. Six of the planets, the six largest possible dwarf planets, and many of the smaller bodies are orbited by natural satellites, usually termed "moons" after the Moon. Each of the outer planets is encircled by planetary rings of dust and other small objects.

The solar wind, a stream of charged particles flowing outwards from the Sun, creates a bubble-like region in the interstellar medium known as the heliosphere. The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium; it extends out to the edge of the scattered disc. The Oort cloud, which is thought to be the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere. The Solar System is located in the Orion Arm, 26,000 light-years from the center of the Milky Way galaxy. The Space Lover (talk) 05:26, 22 June 2021 (UTC)