How big is this asteroid, and what would happen if it hit Earth?

Approximately 300 meters across, something of that size will penetrate
through the atmosphere rapidly and reach the ground in one piece, the
atmosphere protects us from asteroids of smaller sizes. Something of
this size would not disintegrate. Transitional size range depends on the
makeup of the asteroid, but the rocky asteroid: 50 meters. Larger than
that (3 meters hit once a month) sofa-sized, or smaller ones, too,
computer-size;

What are the chances it will strike on April 13, 2029?

There's some confusion because the initial concern was for the year
2029; we were able to rule out the possibility of impact in that year,
since the orbits cross, they intersect in 3 D, these orbits actually
intersect in 3D, so it's a question of timing. When Earth reaches the
crossing point ; can't yet rule out the possibility of impact in later
years, the main reason this object was interesting in the first place is
that the encounter in 2029 has a large possibility of impact for a
number of days; as we continued to observe it, as we found, data in the
archives was found for a year ago, in March, we could say it would not
hit. I think it's not generally appreciated that asteroid predictions
change from day to day. A correct calculation on one day can be altered
the next day by new data.

IMPACT RULED OUT: our knowledge of the orbit has been improved by , esp.
radar, those measurements are very precise and allow us to make a more
accurate prediction of how it will pass us. Sub-asteroid point: It will
pass I believe it's in the Before we uncovered old data and got radar
data, there was much less data from which to computer how it would pass
us, there was not enough data to say which side it would pass on, or
perhaps it would even hit the Earth. For a while the uncertainty was
similar to the earth-moon distance.

The uncertainty is much smaller how. There's no possibility of an
impact. You cannot be it's no negligible, 1 x 10\^10 or less.

Post-encounter: Earth will deflect the path of the asteroid,
calculations for later years take that into account, it's true that the
uncertainty, Earth's gravity magnifies that ucertainty dramatically. 100
km in the flight path could mean the difference, later, between Earth
impact and not.

Two ways to improve things quickly: observing night to night, increasing
the length of time can slowly decrease the uncertainties, quick ways:
find observations from many months or years earlier, and radar data!

There's a desire to observe this thing earlier than 2029.

BENDING IN 2029????????? 30 degrees

UNCERTAINTIS: CERES, PALLAS, VESTA we account for, but not other
asteroids. This asteroid's orbit is mostly interior to Earth's orbit.
This is not expected to be a large error source. Yarkosky acceleration
might have a small effect over a very long term.

Don't forget! It's amazing we know the orbit as well as we do. It's been
observed itinitally only as a point moving across the sky, there's no
infor about how far away it is. Until January, we didn't even know how
far away the asteroid was---then we did radar observations in January.
Orbits are inferred from a series of partial measurements of its orbits,
we know about how objects move at different distances.

What are the possible orbit-bending consequences of the encounter with
Earth?

Has any asteroid that didn't actually hit Earth been so bright? (3^rd^
magntitude)

This is the brightest of any asteroid---period. Discounting those that
enter Earth's atmosphere.

How many similar-sized asteroids are "out there," as yet undiscovered?

There are In that size range, the number in the Near-Earth category are
10,000 that's the total number we would expect. NE means it can 1.3 AU
closest approach to the Sun. In the 1 km range, the estimated population
is 1200. 1 km and above are the asteroids that can cause global
catastrophe. 300 meters would have serious regional consequences.
Continent-wide, or if it hits in the ocean, shores could experience
large tsuamis.

Are these kinds of objects good for, say, asteroid mining?

If this object had been observed for, say, 100 years, we could run the
orbit back 1000 years. Ceres, the first asteroid ever discovered, we
have tracked that for 200 years, and we know its position wo within 10
km or so, and we can run that object back and forth for 1000 years
accurately.

What can se wee? Radar is the best tool to examine an asteroid when it
comes close to Earth, we'll be able to get fantastic images, movies of
rotation, the dielectric constant, a property of what the surface is
made out of, we'll get an excellent shape model. We might even, by
observing---rubble pile or monolithic object, we'll see if there are any
changes in the asteroid, optical spectra will determine the mineroligy
of the surface;

Just because the asteroid is coming close does not mean it is easier to
get to; it's passing by us at a certain velocity 6 km/s or so it's hard
to get a spacecraft to 6 km/s velocity.

Small but nagging possibility that it would hit us in later years. Study
it in detail before 2029, improve our orbit knowlwdge via a transponder.
We would vast;y improve our knowledge of its orbit. It's going to be
difficult to observe because it will spend time in the daylight GOOD
QUESTIONS: do we have enough opportunities to observe to reduce orbit
uncertainties before 2029? Difficult. There will be periods when it will
observabke with radar. 2017? Check with Don or Jon G. radar We need to
know where it is to within 10 km. WHAT IS THE CURRENT UNCERTAINTY in
2029? WHAT ABOUT NOW? (probably several hundred km)

This is a good candidate for an asteroid mission, but not merely to
place a transponder on this object.