Final Product (FOIA 23-F-0010)

Are Much Tougher than Solar Systelll
Rocks!
Figures from the new paper by Amir Siraj & Aui Loeb (September 20, 2022)
In a new paper > with my student,
Amir Siraj, we have identified a second interstellar meteor, IM2, in the CNEOS fireball
catalog > of NASA. The two
interstellar meteors are meter-scale objects that collided with Earth from a trajectory that was
gravitationally unbound to the Sun. In other words, the objects arrived to the Solar system from
interstellar space and were moving faster than the escape speed from the Sun when they were
collected by the "fishing net" of the Earth's atmosphere.
Aui Loeb (left) and Amir Siraj (right) at Loeb's Harvard office; Photograph taken on September 15, 2022.
The first interstellar meteor, CNEOS 2014-01-08 (IMt), that Amir and I discovered in
2019 >, was confirmed at
the 99.999% confidence level by a letter > from the US Space Command to NASA. The second interstellar meteor we just
discovered, CNEOS 2017-03-09 (IM2), was ten times more massive and roughly a meter in size. It
was moving at a speed of 40 (compared to 60 for IM1) kilometers per second relative to the Local
Standard of Rest >, the local frame of
reference of the Milky Way that averages over the motions ofall the stars in the vicinity ofthe Sun.
Remarkably, both IMt and IM2 disintegrated low in the Earth's atmosphere despite their unusually
high speeds. The air ram pressure, which is the product ofthe air mass density and the square ofthe
meteors' speed when they explode into fireballs, provides an estimate for the yield strength of their
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