aRecently, I've got many emails about 2002 NT7 although it is long ago. Asteroid 2002 NT7: Low-Probability of Earth Impact in 2019 Asteroid 2002 NT7 currently heads the list on our IMPACT RISKS Page because of a low-probability Earth impact prediction for February 1, 2019. While this prediction is of scientific interest, the probability of impact is not large enough to warrant public concern. Discovered on July 9, 2002 by the LINEAR team, asteroid 2002 NT7 is in an orbit, which is highly inclined with respect to the Earth's orbit about the sun and in fact nearly intersects the orbit of the Earth. While the orbits of Earth and 2002 NT7 are close to one another at one point in their respective orbits, that does not mean that the asteroid and Earth themselves will get close to one another. Just after an asteroid like 2002 NT7 is discovered, the limited number of observations available do not allow its trajectory to be tightly constrained and the object's very uncertain future motion often allows a very low probability of an Earth impact at some future date. Just such a low probability impact has been identified for February 1, 2019 and a few subsequent dates. Moreover, we have shields! 1. Moon shield
2002 NT7 is a popular asteroid which is likely to strike the earth on 2019. It becomes popular due to media. Although Nasa announced "the probability of impact is not large enough to warrant public concern" 
Asteroids that coming toward the earth are sometimes blocked by moon. Moreover, some are attracted by moon gravity and fall on the moon.
2. Atmosphere shield
Asteroids have very fast very fast velocity of kilometers per second. When they pass the atmosphere, they may experience huge fractions and become smaller.
So, you may be clear about NT7. It has very ...extremely low probability to strike the earth.
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BUT..
What if other large asteroid strikes earth in the future...
What if there is a K-T extinction event of 68 millions years ago in near future?
We have one more shield...
3. Technology shield
We have technology to destroy asteroids in the space! or to change its path. So, no need to fear we will extinct like dinosaurs.
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