And building one would indeed open up at the very least the inner solar system to us.
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The data are the orbits of comets that are likely to have been first-time visitors to the inner solar system.
Added up over the whole sky, this suggested that the belt might contain a billion or more comets waiting to be unleashed on the inner solar system.
"This appears to be this comet's first-ever journey into the inner Solar System and it is expected to pass much closer to the Sun than most comets, " said Tony Farnham of the University of Maryland.
Cheng says the comet is likely making its first visit to the inner solar system from the Oort cloud, a reservoir of hundreds of millions of comets encircling our solar system at a distance of about a light year.
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Most are transient visitors to the vicinity of earth their orbits are so long that many of those arriving now (such as Hale-Bopp) must have made any previous visit to the inner solar system before the beginning of recorded history.
It is thought to be just over 100m years old (Apollo 17 brought back material from the site, which allowed it to be dated), and it is reckoned by Dr Bottke to be the result of the moon encountering one of the first of Baptistina's progeny to arrive in the inner solar system.
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And the hole's outer edge is roughly where rocky planets, like the inner planets of this solar system (including the earth), are expected to be.
Small planets, like the inner four in our own solar system, are rocky - larger ones, like the outer four, aren't much more than balls of gas.
Without it such a galaxy's outer parts would spin more slowly than the inner ones (just as the outer planets of the solar system move around the sun more slowly than the earth does).
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