"Lazarus Comets" Return to Life After Millions of YearsQuote
Millions of years ago the the main belt of asteroids between the orbits of Mars and Jupiter was populated by thousands of active comets. This population aged and the activity subsided. What we see today is the residual activity of that past. Twelve of those rocks are true comets that were rejuvenated after their minimum distance from the Sun was reduced a little. The little extra energy they received from the Sun was then sufficient to revive them from the graveyard. "These objects are the 'Lazarus comets', returning to life after being dormant for thousands or even millions of years," says astronomer Prof. Ignacio Ferrin. "Potentially any one of the many thousands of their quiet neighbors could do the same thing."
"We found a graveyard of comets," said FerrÃn. "Imagine all these asteroids going around the Sun for aeons, with no hint of activity. We have found that some of these are not dead rocks after all, but are dormant comets that may yet come back to life if the energy that they receive from the Sun increases by a few per cent."
The researchers, led by Anitoquia's Ignacio Ferrin, describe how some of these objects, inactive for millions of years, have returned to life. The team publish their results in the Oxford University Press journal Monthly Notices of the Royal Astronomical Society.
Comets are amongst the smallest objects in the Solar System, typically a few km across and composed of a mixture of rock and ices. If they come close to the Sun, then some of the ices turn to gas, before being swept back by the light of the Sun and the solar wind to form a characteristic tail of gas and dust.
Most observed comets have highly elliptical orbits, meaning that they only rarely approach the Sun. Some of these so-called long period comets take thousands of years to complete each orbit around our nearest star. There is also a population of about 500 short period comets, created when long period comets pass near Jupiter and are deflected in orbits that last anything between 3 and 200 years. Although uncommon events, comets also collide with Earth from time to time and may have helped bring water to our planet.
(http://www.dailygalaxy.com/.a/6a00d8341bf7f753ef0192ac54447d970d-pi)
(http://www.dailygalaxy.com/.a/6a00d8341bf7f753ef0192ac544581970d-pi)
http://www.dailygalaxy.com/my_weblog/2013/08/lazarus-comets-return-to-life-after-millions-of-years.html
Love finding information like this, it makes the world
seem exciting, we know what we know now, only until
tomorrow comes and brings something fresh! :)