1.
Catalina Sky Survey
–
Catalina Sky Survey is a project to discover comets and asteroids, and to search for near-Earth objects. More specifically, CSS is to search for any potentially hazardous asteroids that may pose a threat of impact and its southern hemisphere counterpart, the Siding Spring Survey was closed in 2013 due to loss of funding. CSS supersedes the photographic Bigelow Sky Survey, Catalina Sky Survey utilized two US telescopes, a 1.5 meter f/2 telescope on the peak of Mt. Lemmon, and a 68 cm f/1.7 Schmidt telescope near Mt. Bigelow. The CSS southern hemisphere counterpart, the Siding Spring Survey, used a 0.5 meter f/3 Uppsala Schmidt telescope at Siding Spring Observatory in Australia, all sites use identical, thermo-electrically cooled cameras and common software that was written by the CSS team. The cameras are cooled to approximately −100 °C so their dark current is about 1 electron per hour and these 4096×4096 pixel cameras provide a field of view of 1 degree square on with the 1. 5-m telescope and nearly 9 square degrees with the Catalina Schmidt. Nominal exposures are 30 seconds and the 1. 5-m can reach objects fainter than 21.5 V in that time, CSS typically operates every clear night with the exception of a few nights centered on the full moon. The southern hemispheres SSS in Australia ended in 2013 after funding was discontinued, in 2005, CSS became the most prolific NEO survey surpassing Lincoln Near-Earth Asteroid Research in total number of NEOs and potentially hazardous asteroids discovered each year since. CSS discovered 310 NEOs in 2005,396 in 2006,466 in 2007, for a complete listing of all minor planets discovered by the Catalina Sky Survey, see the index section in list of minor planets. The CSS team is headed by Eric Christensen of the Lunar, the full CSS team is, Robert H. McNaught Gordon J. Garradd The CSS has helped with Astronomy Camp showing campers how they detect NEOs. They even played a role in an exercise with the 2006 Adult Astronomy Camp ending up with a picture that was featured on Astronomy Picture of the Day. Catalina Sky Survey Website Overview and history
2.
Mount Lemmon Observatory
–
The MLO site was first developed in 1954 as Mount Lemmon Air Force Station, a radar installation of the Air Defense Command. Upon transfer to the Steward Observatory 1970, the site was converted to an infrared observatory, until 2003, a radar tower operated from Fort Huachuca was used to track launches from the White Sands Missile Range in New Mexico and Vandenberg Air Force Base in California. The 1.52 m Steward Observatory Telescope is a Cassegrain reflector used for the Mount Lemmon Survey and it was built in the late 1960s and first installed at Catalina Station on Mount Bigelow, which is nearby in the Santa Catalina Mountains. It was moved to Mt. Lemmon in 1972, and then re-housed in its current location in 1975 and its original metal primary mirror performed poorly and was replaced in 1977 with a glass mirror made of Cer-Vit. It is one of the used by students at Astronomy Camp. It discovered 2011 AG5, an asteroid which achieved 1 on the Torino Scale, a 1.52 m Dahl-Kirkham optical/near infrared telescope began operating in 1970, and is the only instrument at the Mt. Lemmon Observing Facility of the University of Minnesota. It is of the general design as the 1.5 m Steward telescope. The original metal mirror performed poorly and was replaced with a Cer-Vit mirror in 1974, the University of California, San Diego was originally a partner of UMN in operating the telescope. A1.02 m reflecting telescope of an unusual Pressman-Camichel design is used by the CSS to provide automated follow up observations of newly discovered Near-Earth Objects and it was originally located at Catalina Station and was moved to MLO in 1975. It was refurbished in 2008 and placed in a new dome in 2009 before being integrated into CSS operations, a 1.0 m robotic telescope installed in 2003 is the only instrument of the Mt. Lemmon Optical Astronomy Observatory operated by the Korea Astronomy and Space Science Institute. The 0.81 m Schulman Telescope is a Ritchey-Chrétien reflector built by RC Optical Systems and it is operated by the Mt. Lemmon SkyCenter and is Arizonas Largest dedicated public observatory. A0.7 m reflecting telescope installed in 1963 at Catalina Station was moved to MLO in 1972, a 0.6 m Ritchey-Chrétien reflector was built by RC Optical Systems and is operated by the Mt. Lemmon SkyCenter. The 0.5 m John Jamieson Telescope was donated to UA in 1999 and it is optimized for near infrared observing and is operated by the Mt. Lemmon SkyCenter
3.
Minor planet
–
A minor planet is an astronomical object in direct orbit around the Sun that is neither a planet nor exclusively classified as a comet. Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, as of 2016, the orbits of 709,706 minor planets were archived at the Minor Planet Center,469,275 of which had received permanent numbers. The first minor planet to be discovered was Ceres in 1801, the term minor planet has been used since the 19th century to describe these objects. The term planetoid has also used, especially for larger objects such as those the International Astronomical Union has called dwarf planets since 2006. Historically, the asteroid, minor planet, and planetoid have been more or less synonymous. This terminology has become complicated by the discovery of numerous minor planets beyond the orbit of Jupiter. A Minor planet seen releasing gas may be classified as a comet. Before 2006, the IAU had officially used the term minor planet, during its 2006 meeting, the IAU reclassified minor planets and comets into dwarf planets and small Solar System bodies. Objects are called dwarf planets if their self-gravity is sufficient to achieve hydrostatic equilibrium, all other minor planets and comets are called small Solar System bodies. The IAU stated that the minor planet may still be used. However, for purposes of numbering and naming, the distinction between minor planet and comet is still used. Hundreds of thousands of planets have been discovered within the Solar System. The Minor Planet Center has documented over 167 million observations and 729,626 minor planets, of these,20,570 have official names. As of March 2017, the lowest-numbered unnamed minor planet is 1974 FV1, as of March 2017, the highest-numbered named minor planet is 458063 Gustavomuler. There are various broad minor-planet populations, Asteroids, traditionally, most have been bodies in the inner Solar System. Near-Earth asteroids, those whose orbits take them inside the orbit of Mars. Further subclassification of these, based on distance, is used, Apohele asteroids orbit inside of Earths perihelion distance. Aten asteroids, those that have semi-major axes of less than Earths, Apollo asteroids are those asteroids with a semimajor axis greater than Earths, while having a perihelion distance of 1.017 AU or less. Like Aten asteroids, Apollo asteroids are Earth-crossers, amor asteroids are those near-Earth asteroids that approach the orbit of Earth from beyond, but do not cross it
4.
Amor asteroid
–
The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of Earth from beyond, but do not cross it, most Amors cross the orbit of Mars. The two moons of Mars, Deimos and Phobos, may be Amor asteroids that were captured by Marss gravity, the most famous member of this group is 433 Eros, which was the first asteroid to be orbited and then landed upon by a human probe. There are three general criteria which an asteroid must meet to be considered a member of the Amor asteroid class, to be considered near, the asteroid must come closer to Earth than to any other major planet. The closest planet to Earth is Venus, which can come as close as 0.27 AU, therefore, an Amor asteroid must come within 0.30 AU of Earths orbit. The asteroids orbit must be outside the orbit of Earth, asteroids that come close to Earth whose orbits are inside Earths orbit are considered Apohele asteroids. The asteroids orbit must not cross Earths orbit, the most commonly used definition of this is that it never orbits closer to the Sun than Earths average distance from the Sun. A more strict definition is that at any point along the asteroids orbit and this takes into consideration the fact that Earths orbit ranges between 0.983 and 1.016 AU from the Sun. It is more difficult to sort out the Amor asteroids from the non-Amor asteroids using this definition, however. These three criteria boil down to a single test for membership, If an asteroid has a perihelion between 1.000 AU and 1.300 AU, it is an Amor asteroid. Any asteroid with this trait is considered an Amor-class asteroid, regardless of its axis, eccentricity, aphelion, inclination, physical properties, orbital stability. An asteroid belongs to the Amor group if, Its orbital period is greater than one year and this is equivalent to saying that its semi-major axis is greater than 1.0 AU. Its orbit does not cross Earths orbit and that is, its lowest point is higher than Earths highest point. It is an object, that is, its perihelion distance q <1.3 AU. In summary, a >1.0 AU and 1.017 AU < q <1.3 AU, there are 6051 Amor asteroids currently known. 960 of them are numbered, and 73 of them are named, Amor asteroids can be partitioned into four subgroups, depending on their average distance from the Sun. The Amor I subgroup consists of Amor asteroids whose semi-major axes are in between Earth and Mars and that is, they have a semi-major axis between 1.000 and 1.523 AU. Less than one fifth of Amor asteroids belong to this subgroup, Amor I asteroids have lower eccentricities than the other subgroups of Amors
5.
Near-Earth object
–
A near-Earth object is any small Solar System body whose orbit brings it into proximity with Earth. By definition, a solar system body is a NEO if its closest approach to the Sun is less than 1.3 astronomical unit and it is now widely accepted that collisions in the past have had a significant role in shaping the geological and biological history of the Earth. NEOs have become of increased interest since the 1980s because of increased awareness of the potential danger some of the asteroids or comets pose, and mitigations are being researched. In January 2016, NASA announced the Planetary Defense Coordination Office to track NEOs larger than 30 to 50 meters in diameter and coordinate an effective threat response, NEAs have orbits that lie partly between 0.983 and 1.3 AU away from the Sun. When a NEA is detected it is submitted to the IAUs Minor Planet Center for cataloging, some NEAs orbits intersect that of Earths so they pose a collision danger. The United States, European Union, and other nations are currently scanning for NEOs in an effort called Spaceguard. In the United States and since 1998, NASA has a mandate to catalogue all NEOs that are at least 1 kilometer wide. In 2006, it was estimated that 20% of the objects had not yet been found. In 2011, largely as a result of NEOWISE, it was estimated that 93% of the NEAs larger than 1 km had been found, as of 5 February 2017, there have been 875 NEAs larger than 1 km discovered, of which 157 are potentially hazardous. The inventory is much less complete for smaller objects, which still have potential for scale, though not global. Potentially hazardous objects are defined based on parameters that measure the objects potential to make threatening close approaches to the Earth. Mostly objects with an Earth minimum orbit intersection distance of 0.05 AU or less, objects that cannot approach closer to the Earth than 0.05 AU, or are smaller than about 150 m in diameter, are not considered PHOs. This makes them a target for exploration. As of 2016, three near-Earth objects have been visited by spacecraft, more recently, a typical frame of reference for looking at NEOs has been through the scientific concept of risk. In this frame, the risk that any near-Earth object poses is typically seen through a lens that is a function of both the culture and the technology of human society, NEOs have been understood differently throughout history. Each time an NEO is observed, a different risk was posed and it is not just a matter of scientific knowledge. Such perception of risk is thus a product of religious belief, philosophic principles, scientific understanding, technological capabilities, and even economical resourcefulness.03 E −0.4 megatonnes. For instance, it gives the rate for bolides of 10 megatonnes or more as 1 per thousand years, however, the authors give a rather large uncertainty, due in part to uncertainties in determining the energies of the atmospheric impacts that they used in their determination
6.
Potentially hazardous object
–
A potentially hazardous object can be known not to be a threat to Earth for the next 100 years or more, if its orbit is reasonably well determined. Potentially hazardous asteroids with some threat of impacting Earth in the next 100 years are listed on the Sentry Risk Table, as of March 2017 there are 1,786 known potentially hazardous asteroids and only 205 have an observation arc shorter than 30 days. Of the known PHAs,157 are believed to be larger than one kilometer in diameter, a calculated diameter is only a rough estimate, as it is inferred from the objects varying brightness—observed and measured at various times—and the assumed, yet unknown reflectivity of its surface. Most of the discovered PHAs are Apollo asteroids and fewer belong to the group of Aten asteroids, after several astronomical surveys, the number of known PHAs has increased tenfold since the end of the 1990s. These surveys have led to a number of 15,802 discovered near-Earth objects. Most of them are asteroids, with just some 106 near-Earth comets, the Minor Planet Centers website Unusual Minor Planets also publishes detailed statistics for these objects. This is big enough to cause devastation to human settlements unprecedented in human history in the case of a land impact. Such impact events occur on average once per 10,000 years. NEOWISE data estimates that there are 4,700 ±1,500 potentially hazardous asteroids with a greater than 100 meters. As of 2012, an estimated 20 to 30 percent of these objects have been found, Asteroids larger than 35 meters across can pose a threat to a town or city. The diameter of most small asteroids is not well determined and can only be estimated based on their brightness, for this reason NASA and the Jet Propulsion Laboratory use the more practical measure of absolute magnitude. Any asteroid with a magnitude of 22. The NASA near-Earth object program uses an assumed albedo of 0.13 for this purpose, in May 2016, the asteroid size estimates arising from the Wide-field Infrared Survey Explorer and NEOWISE missions have been questioned, but the criticism has yet to undergo peer review. Several astronomical survey projects such as Lincoln Near-Earth Asteroid Research and Catalina Sky Survey continue to search for more PHOs, both professional and amateur astronomers participate in such monitoring. This is a reflection of the character of the Solar System. The two main scales used to categorize the impact hazards of asteroids are the Palermo Technical Impact Hazard Scale, the lowest numbered PHA is 1566 Icarus. The largest known Potentially hazardous asteroid is 1999 JM8 with a diameter of ~7 km, below is listed the largest PHA discovered in a given year. Historical data of the number of discovered PHA since 1999 are displayed in the bar charts—one for the total number
. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 30 January 2018.
