ludzkie-ciekawostki: Near-Earth object

Evidence: 45 • authority: 72

A near-Earth object (NEO) is by definition any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance (astronomical unit, AU). This definition applies to the object's orbit around the Sun, rather than its current position, thus an object with such an orbit is considered a NEO even at times when it is far from making a close approach of Earth. If a NEO's orbit crosses the Earth's orbit, and the object is larger than 140 meters (460 ft) across, it is, by definition, considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but about a third of a percent are comets. There are over 37,0…

Evidence: 43 • authority: 88

The European Commission funded NEO-MAPP project in support of the ESA Hera mission: Near-Earth Object Modelling And Payload for Protection. NEO-MAPP stands for Near Earth Object Modelling And Payload for Protection. This project is funded by the H2020 program of the European Commission and addresses the topic "Advanced research in Near Earth Objects (NEOs) and new payload technologies for planetary defence" (SU-SPACE-23-SEC-2019).NEO-MAPP selected as primarily reference scenario the ESA Hera mission, which has recently been approved by the ESA Council at Ministerial Level, Space19+, in November 2019 for launch in 2024. The main goal of NEO-MAPP is to support the dev…

Evidence: 38 • authority: 72

The Solar System is the gravitationally bound system of the Sun and the masses that orbit it, most prominently its eight planets, of which Earth is one. The Solar System is an isolated single-star planetary system (not part of a larger star system) within the Milky Way Galaxy. The system formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, creating the Sun and a protoplanetary disc from which the orbiting bodies assembled. The Sun accounts for 99.86% of the Solar System's total mass. Inside the Sun's core, hydrogen is fused into helium, releasing energy that is emitted through the Sun's photosphere. This creates the heliosphere and a decreasing temperature…

Evidence: 38 • authority: 72

In August 2006, the International Astronomical Union (IAU) adopted a new definition of the term planet, which stated that, in the Solar System, a planet is a celestial body that: is in orbit around the Sun, has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and has "cleared the neighbourhood" around its orbit. A non-satellite body fulfilling only the first two of these criteria (such as Pluto, which had hitherto been considered a planet) is classified as a dwarf planet and not a planet. A non-satellite body fulfilling only the first criterion is termed a small Solar System body (SSSB). An alternate proposal included dwarf planets as a subcategory of planets, but I…

Evidence: 38 • authority: 72

This article includes a list of the most massive known objects of the Solar System and partial lists of smaller objects by observed mean radius. These lists can be sorted according to an object's radius and mass and, for the most massive objects, volume, density, and surface gravity, if these values are available. These lists contain the Sun, the planets, dwarf planets, many of the larger small Solar System bodies (which includes the asteroids), all named natural satellites, and a number of smaller objects of historical or scientific interest, such as comets and near-Earth objects. Many trans-Neptunian objects (TNOs) have been discovered; in many cases their positions in this list are appro…

Evidence: 37 • authority: 72

In astronomy, a co-orbital configuration is a configuration of two or more astronomical objects (such as asteroids, moons, or planets) orbiting at the same, or very similar, distance from their primary; i.e., they are in a 1:1 mean-motion resonance. (Or 1:−1 if orbiting in opposite directions.) There are several classes of co-orbital objects, depending on their point of libration. The most common and best-known class is the trojan, which librates around one of the two stable Lagrangian points (Trojan points), L4 and L5, 60° ahead of and behind the larger body respectively. Another class is the horseshoe orbit, in which objects librate around 180° from the larger body. Objects librating arou…

Evidence: 25 • authority: 88

The recent dynamical past of the low perihelion NEO population. <p>The NEO population model derived by Granvik et al. (2016,2017,2018) suggested that there is an overestimate of objects in low perihelion distance (q) orbits when compared to the observed population. The remedy to this discrepancy was to include a super-catastrophic disruption of objects when they crossed an average disruption distance, defined as q*=0.076 au. The mechanism responsible for destroying such objects is not determined yet, but it is believed to be thermal in nature.</p> <div>In this study, we aim to determine which members of the known NEO population have approached close to the Sun in their recent past and may e…

Evidence: 25 • authority: 92

Non-gravitational acceleration indicative of cometary activity of near-Earth object.. The activity of comets when they approach the Sun usually manifests visibly with the appearance of a dust and gas coma, and in turn non-gravitational accelerations perturbing their motion. However, there exist objects that are morphologically inactive and yet exhibit non-gravitational accelerations. Here we show that astrometry from 1998 to 2025 of near-Earth object (875163) 1998 SH 2 reveals orbital perturbations consistent with cometary outgassing. Although no cometary activity was evident in archival images, large-aperture telescopic observations show a weak low-surface-brightness tail and prove that 19…

Evidence: 25 • authority: 72

A geocentric orbit, Earth-centered orbit, or Earth orbit involves any object orbiting Earth, such as the Moon or artificial satellites. In 1997, NASA estimated there were approximately 2,465 artificial satellite payloads orbiting Earth and 6,216 pieces of space debris as tracked by the Goddard Space Flight Center. More than 16,291 objects previously launched have undergone orbital decay and entered Earth's atmosphere. A spacecraft enters orbit when its centripetal acceleration due to gravity is less than or equal to the centrifugal acceleration due to the horizontal component of its velocity. For a low Earth orbit, this velocity is about 7.8 km/s (28,100 km/h; 17,400 mph); by contrast, the…