Astronomers find unexpected comets in outer reaches of solar system
Using data from the WISE space telescope, astronomers have found that there are more comets lurking in the far reaches of the solar system than they had predicted.
Scientists found that there are about seven times more long-period comets measuring at least 0.6 miles (1 kilometer) across than had been predicted previously. They also found that long-period comets are on average up to twice as large as “Jupiter family comets,” whose orbits are shaped by Jupiter’s gravity and have periods of less than 20 years. Researchers also observed that in eight months, three to five times as many long-period comets passed by the Sun than had been predicted.
These are comets whose orbits never allow them to come close to the inner solar system, which allows them to remain puffy and large.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Using data from the WISE space telescope, astronomers have found that there are more comets lurking in the far reaches of the solar system than they had predicted.
Scientists found that there are about seven times more long-period comets measuring at least 0.6 miles (1 kilometer) across than had been predicted previously. They also found that long-period comets are on average up to twice as large as “Jupiter family comets,” whose orbits are shaped by Jupiter’s gravity and have periods of less than 20 years. Researchers also observed that in eight months, three to five times as many long-period comets passed by the Sun than had been predicted.
These are comets whose orbits never allow them to come close to the inner solar system, which allows them to remain puffy and large.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Puffy and large means just full of water. Something easy to harvest way out there.
“These are comets whose orbits never allow them to come close to the inner solar system, which allows them to remain puffy and large.”
A list of these long period (>200 year orbit but <1000 year) comets is here.
https://en.wikipedia.org/wiki/List_of_long-period_comets
One can define "come close to the inner solar system" as less than the distance of the asteroid belt (~3 AU). I count ~100 of these comets with a perihelion of <3 AU out of the list of 116. 36 of the comets on this list pass less than 1 AU from the Sun.
Thus, I do not think your statement is correct.
The time frame of a mere 200 years seems infinitesimally short in the long time of the solar system (5 billion years), so they should have passed millions of times through the inner solar system over that period.
Also look at this list.
https://en.wikipedia.org/wiki/List_of_near-parabolic_comets
One of those has an orbit period estimated to be 130,000,000 years! That one would have passes as close as 4.2 AU ~38 times over the solar system age.