The Earth exists in a dangerous environment.
Cosmic bodies, like asteroids and comets, are constantly zooming throughspaceand often crash into our planet.
Most of these are too small to pose a threat, but some can because for concern.
To find the answers to these questions, one has to know what near-Earth objects are out there.
To date,NASAhas tracked only an estimated40% of the bigger ones.
Surprise asteroids have visited Earth in the past and will undoubtedly do so in the future.
When they do appear, how prepared will humanity be?
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Larger objects 0.6 miles (1 km) or more could have global effects and even cause mass extinctions.
Itwiped out most plant and animal specieson Earth, including the dinosaurs.
But smaller objects can also cause significant damage.
In 1908, an approximately 164-foot (50-meter) celestial body exploded over theTunguskariver in Siberia.
Itleveledmore than 80 million trees over 830 square miles (2,100 square km).
The next asteroid of substantial size to potentially hit Earth is asteroid 2005 ED224.
NASA has been steadily finding and tracking near-Earth objects since the 1990s.
NASAsurpassed the 90% goalin 2011.
About30 new objectsare added each week.
An asteroid the size of a football field dubbed the City-killer passedless than 45,000 milesfrom Earth in 2019.
An asteroid the size of a 747 jetcame closein 2021 as did a 0.6-mile (1-km) wideasteroidin 2012.
Each of these was discovered onlyabout a daybefore they passed Earth.
This may be a problem, as some surprise asteroids do not miss us.
In 2008, astronomers spotted a smallasteroidonly 19 hours before it crashed into rural Sudan.
Image: NASA/JHUAPL/Steve Gribben
What can be done?
To protect the planet from cosmic dangers, early detection is key.
If astronomers find a dangerous object, there arefour waysto mitigate a disaster.
The first involves regional first-aid and evacuation measures.
Thelarge asteroid Didymosand its small moon currently pose no threat to Earth.
Theasteroid Bennuis 1,620 feet (490 meters) in diameter.
Spending on planetary defense
In 2021, NASAs planetary defense budget was$158 million.
This is an important question to ask when one considers the potential consequences.
Investing in planetary defense is akin to buying homeowners insurance.
The likelihood of experiencing an event that destroys your house is very small, yet people buy insurance nonetheless.
A bigger impact could quite literally wipe out most species on Earth.
