An Australian astronomer, an amateur Anthony Wesley, observed Jupiter on July 19, 2009, spotting a black Earth-sized spot on the surface, suggesting that something big had hit this planet of the solar system. Glenn Orton of NASA confirmed that it was a previously unobserved comet or asteroid. Of course, the probability that something will hit the Earth is quite small, and yet the fact that such an object "has not previously been seen" is a very worrying fact.

https://thelede.blogs.nytimes.com/2009/07/21/amateur-astronomer-finds-new-earth-size-impact-mark-on-jupiter/

http://edition.cnn.com/2009/TECH/space/07/21/jupiter.nasa.meteor.scar/index.html

On February 15, 2013, a meteorite landed in Chelyabinsk, the fragments of which were later found in the immediate vicinity. It did not do too much damage; windows in the buildings were broken

 https://www.youtube.com/watch?v=dpmXyJrs7iU

TOP 5 meteors falling - youtube video. We draw your attention to the fact that this is not so rare.

https://www.youtube.com/watch?v=ULBJwz97-4k

You can also look at simulations of 10 - 20 - 50 meters and larger asteroids.

To observe everything on Earth is VLT

www.youtube.com/results?search_query=vl+telescope

You will have ELT

www.youtube.com/results?search_query=elt+mirror

There are also larger and smaller telescopes, and even amateurs can discover something. In Space we also have telescopes.

https://en.wikipedia.org/wiki/List_of_space_telescopes

But is there anything in space that can look behind the Sun ? And some 10 such specialized telescopes pointed in other directions looking specifically for such objects?

Elon Musk has launched his car with a spaceman in Space

www.npr.org/sections/13.7/2018/02/07/583961486/our-ancestors-elon-musk-and-the-first-car-in-space

Here - a 400-meter-long interstellar guest - arrived at a destination with a speeding connection of 95,000km/h (26km/sec). Passed by the Earth. 

www.youtube.com/results?search_query=1i%2F20017+U1

www.youtube.com/watch?v=fbL1ZoAQgUU

You can search for 2014-JO25, Toutatis, 199-AN10, 2004 BL86, 1998 QE2, 2012 TC4, 2012 DA14, AJ129, 1i/20017U1.

However, some of these things that fly far enough or can hit the Earth are rather precisely calculated comets that return to the solar system for a certain period of time and their distance to the Earth is known. Except for the fact that they are somewhere distant or not close enough to some other space object that slightly changes this trajectory and speed. There are also all kinds of distant space visitors, whose size, speed, and trajectory are only known when they fly far enough or hit the Earth. It should immediately be noted that the objects that come from the Sun are less likely to be observed from the Earth, because none of their large telescope mirrors can not be fired against the sun, because they do not want to burn them. This would require some kind of telescope, which can find some kind of orbit passing from the Earth; in theory, maybe to the other side of the Sun precisely on the Earth's orbit and send information back to Earth through some kind of retransmission station. As the light from the Sun takes eight minutes to reach the Earth, we will receive information about an approaching comet on Earth in 12 minutes. Simple Mathematics, Pythagoras Triangle. At this time, at a speed of 25km/s, this space object rides 12min x 25km/ sec x 60sec/min =18000km. So, if we wanted to quickly process the information received and shoot it with a some weapon, we would have to figure it out not at the same object, but in the place where it will be according to the forecast. Twelve minutes to receive the information; a further twelve minutes for information rejection and some calculations; giving a total of 24 minutes in which to accurately predict the location of the object. It must have taken exactly 2 x 18000km = 36000km, no more and no less, and if we put it precisely on its side, it will serve closer to the Sun and it will use its trajectory so that it will not crash into the Earth. Maybe even hit the sun and melt. Can we rely on a command with a time delay from the Earth to this equipment, or maybe it should calculate all its parameters and adapt the trajectory? If such a device would orbit somewhere around Jupiter or Saturn, then those distances and time retention would be even more impressive; everything should happen automatically. What can be done with the current technical approach? 

Do we have any kind of telescope that looks after the Sun? No! We have Elon Musk's spaceman in his electric car, Kim, who said he had something; President Trump, who replied that he had more things; Putin, who said that he also had some things, and no one could delay it and it will be like a meteor and then some other people replied that everyone knows it and is ready and some - that do not really believe him. In space, we do not even have a precise warning system that would be able to tell people in a timely manner that people should move away from the coast in the event of something too big falling into the ocean, causing a tsunami, not to mention something that could be fired side by side to prevent this falling in ocean. In addition, we had a very negative experience with the earthquake that caused severe damage not only on Phuket Island, but also hundreds of miles from it. Tsunami speeds were "only" at 800km/h (0.22km/sec) and even in quite distant places people were not aware. 

Some further information about this cosmic guest: composition – stone, iron, ice, some sort of rocks - all this knowledge is important, because as a result of various factors it all either evaporates or splits, or does not crash, and can only be diverted from its course. It should also be noted that the smallest space rock, ice and iron present in the Earth's atmosphere move at such a speed, due to friction, heat and burn up; or at least a large part of their mass burns; or get tangled in pieces. Down on the ground they are the biggest. 

www.youtube.com/watch?v=woafGw2BAxk

This is a video that shows how a space object passes the Earth and how its trajectory changes. One can intuitively think and specialists to mathematically figure out to what point a significant trajectory points to their object slightly to one side or the other and how it changes trajectories. This would be the most effective measure if the object is large enough to crumble it into pieces, to melt it, or to reduce its speed with an explosion. Slightly divert it as it flies closer to Jupiter, Saturn or the Sun and the trajectory changes much more significantly. 

In recent times, the political situation has developed slightly. Without going into details in this article I want to remind you that there are enough weapons on the Earth, including atomic weapons, which can shred everything to pieces. It would be stupid if something crashes down to Earth, raises an enormous tsunami or causes a major catastrophe on land, and then somebody says that it would have been possible to shrink pieces or divert the trajectory with a few rockets. 

What are some of the achievements of the past when trying to make contact or hit a comet and knock something out of it? 

The "Rosetta" probe with its existing Philae laboratory was launched in 2004, and landing at the "67P/Churjumov-Gerasimenko". The comet was 510 million kilometers from Earth, almost three times more than the distance from our planet to the Sun. It cost 1.3 billion euros; the mission had been approved in 1993. 

The mission was to collect comet samples to get an idea of the development of the Earth and other planets. It had ten scientific tools. 

Thorough calculations were used. It rolled through Mars and Earth four times to accelerate with gravity. Then a 31-month hibernation period began - Rosetta was too far from the Sun to employ power solar energy. The hibernation period was interrupted in January and it was "woken up". In total, Rosetta flew over 6.5 billion kilometers to its comet. 

 www.youtube.com/watch?v=mggUVLFPkQg

We use our knowledge of the comet's trajectory and gravity forces to be able to make such calculations. 

To make it all not so "scientific and dry", there are some other problems; one of the main scientists of this project, Matt Taylor. 

www.theguardian.com/science/2014/nov/14/rosetta-comet-dr-matt-taylor-apology-sexist-shirt

He offended some feminists by wearing the wrong shirt. Look for yourself, if space research is more interested in this aspect - Matt Taylor offensive shirt. 

The Deep Impact mission: On July 4, 2005, the spacecraft reached the comet Temple1. The impact module collided with the comet, but the overpass module performed various measurements during and after the impact. 

www.youtube.com/watch?v=dryvDlB1hWA

www.youtube.com/watch?v=h4lpu8HbpFY

The fact that it can hit a comet and knock out several thousand tons of rock and, in the first instance, match its speed for landing, shows that in principle the necessary skills and technologies already exist. Find the space exploration space for Sun.

It will be interesting to hear when national leaders announce that a space observation system for all objects has been set up or at least launched, and that it is possible to shift enough objects from the course or to cut into pieces in order to completely eliminate or minimize their impact on the Earth. 

Update. Already after writing the article, I found this information. You can search by these words - WR12 mission DART 2022 Didymos system

www.nasa.gov/feature/nasa-s-first-asteroid-deflection-mission-enters-next-design-phase

Didymos - a twin asteroid system that circles one another, one is 780 meters in diameter, another 160 meters in diameter. In October 2022 they will be near the Earth. Program scientist Tom Statler says that shoot will come from the largest to the smallest, with a refrigerator-sized kinetic shot at a speed of 6km/sec. Observing from the bigeest asteroid from a large perspective, they will evaluate the possibilities to change orbits of such objects.

All of this, of course, will bring in many valuable knowledge in the event of success. However, all this happens with known orbits of known objects. In order to determine in a timely manner, where, after all the influences from the Sun's gravity interstellar 1i/20017U1, will require much more, much more.

www.youtube.com/watch?v=woafGw2BAxk

UPDATE. https://www.space.com/asteroid-ciose-earth-flyby-orbit-change-2020-qg.html

"Early Sunday morning (Aug. 16), the car-sized 2020 QG zoomed just 1,830 miles (2,950 kilometers) above the Indian Ocean, making the closest known flyby by an asteroid that didn't end up slamming into our planet."