Global killer
A Global Killer (English, German. Global Killer ) is a derived from space object ( asteroid , meteoroid or comet ), whose impact (specialist terminology impact ) caused global devastation. The term is mostly used in connection with impacts on the earth , but can in principle also be applied to impacts on other celestial bodies. An essential feature is that the devastation affects the respective celestial body as a whole and is not only limited locally or regionally. The best-known example of a global killer is the solid that caused the 180 km large Chicxulub crater on the Mexican peninsula of Yucatán about 66 million years ago and is considered to be the main cause of the mass extinction of that time (including the extinction of non-avian dinosaurs ).
term
The term killer expresses that an actual or potential impact can seriously endanger the terrestrial biosphere and cause mass extinction up to the total extinction of all life.
It has long been known that during the history of the earth mass extinctions occurred again and again , in the course of which large parts of flora and fauna were wiped out. The best known of these biological crises occurred at the Cretaceous-Paleogene boundary about 66 million years ago. A conspicuous, worldwide proven anomaly of the element iridium , which occurs very rarely on earth , led to the assumption that the impact of an asteroid at least 10 km in diameter was the cause of the mass extinction at that time.
After the Chicxulub crater was discovered , at least the possibility of a world-wide, life-threatening impact scenario was widely accepted.
Risk assessment
There are essentially two scales for risk assessment : the Turin scale and the Palermo scale . Both take into account the impact risk and the explosive force. However, the Palermo scale is more complex than the Turin scale.
Search programs
The possible threat posed by Global Killer has meant that there are now a number of search programs whose task it is to discover near-earth objects in good time, to determine their size and orbit and to assess the possible risk of collision. The sky is systematically monitored with telescopes.
However, for a long time the danger was considered rather hypothetical. It was not until the impact of Comet Shoemaker-Levy 9 on Jupiter in 1994 that it became clear that such impacts are a real threat. As a result, various search programs were initiated by the USA and the European Union .
LINEAR is an example of such a project . By the end of 2007 alone, more than 220,000 new objects had been found, including over 2,000 earth orbit cruisers. Overall, such search programs have significantly increased the number of known objects.
forecast
Orbits can be calculated from the observations and thus the risk of an impact for a certain period of time can be estimated in advance. The path calculations of the previously known objects have been highly automated since 2002.
2008 TC 3 is considered a successful example of such a prediction . Both the time and the location of the impact could be correctly predicted shortly after the discovery.
However, this also shows the problem of such a prediction: 2008 TC 3 was only discovered 20 hours before the impact. Too short a period for countermeasures or the evacuation of a larger settlement.
Possible or actual global killers
Terrestrial craters at least 100 km in diameter
| Object / crater | Time of impact |
size | Strength | Remarks |
|---|---|---|---|---|
| Vredefort crater | 2,023 ± 5 mya | 320 km × 180 km | largest safely identified meteorite crater on earth | |
| Sudbury crater | 1,850 mya | 250 km × 200 km (originally) | second largest meteorite crater on earth | |
| Chicxulub crater | 66 mya | 180 km | Mass extinction of all non-avian dinosaurs, among others, is discussed. | |
| Woodleigh crater | 360 mya | 120 km | ||
| Popigai | 35 / 33.7 mya | 100 km | ||
| Manicouagan crater | 214 mya | 100 km |
Large impact craters on other celestial bodies
Heavenly body hit |
Object / crater | Time of impact |
size | Strength in TNT equivalent |
Remarks |
|---|---|---|---|---|---|
| Jupiter | Shoemaker-Levy 9 | 16.-22. July 1994 | up to 12,000 km | 800 gigatons | The impact resulted in several dark spots in the atmosphere that were visible for months . The indication of the size relates to the gas bubbles visible from Earth in the Jupiter atmosphere, not to a crater diameter. |
| moon | Maria | 4,200 ± 300 mya | up to 2,568 km | ||
| moon | South Pole Aitken Basin | ? | 2.240 km according to other information: 2.500 km |
largest known crater in the solar system | |
| Mars | Hellas Planitia | 3,700 ± 200 mya | 2,100 km according to other data: 2,000 km × 1,600 km |
second largest known crater in the solar system | |
| Mercury | Caloris Planitia | 3,900 mya | 1,550 km | Largest Mercury crater, probably caused mountain formation on the opposite side of the planet |
Global killer in film
The idea of destructive impacts has led to the disaster film's own subgenre . Examples are Armageddon (1998), Deep Impact (1998), Melancholia (2011), In Search of a Friend for the End of the World (2012) and These Final Hours (2013)
Early forerunners are the Danish film Verdens undergang (German: The fall of the world ) and the American short film The Comet's Come-Back (German: The return of the comet ), both from 1916. In both films, however, the earth becomes through contact with the Tail of a nearby comet threatened.
See also
References and Notes
- ↑ Becky Oskin: Russia's Popigai Meteor Crash Linked to Mass Extinction . livescience, June 13, 2014.
- ↑ a b German translation of the original title, no German title is known.