67P/Churyumov–Gerasimenko – the target comet for Rosetta is currently 583 million kilometers/362 million miles from our Sun and yet she’s sweating it. How far is that? About the distance from Mars to the Sun and back again.
It is a common thing for a comet to lose this much water even more but usually not this far out from the Sun. The rate of “sweat” is enough to fill an Olympic sized pool in three months time.
Comets are made up of ice, mostly. A comet will release gas & dust though research has shown that they also contain carbon dioxide, ammonia, methane and more. It has been speculated that comets might have brought some of the original water and organic materials here to Earth and sprinkled at planets through the Solar System.
Some comets orbit the Sun but most are believed to ‘live’ in a place called the Oort Cloud. (The Oort Coud is a huge spherical cloud that begins~3000-5000 astronomical units from here and is theorized to end as far as 100,000 Astronomical Units / end of the Solar System.) From time to time a comet streaks through the inner Solar System while following its usual orbit; as it gets closer to the Sun some amazing changes occur. Science wise as it gets close to the Sun the ice on the surface of the nucleus begins to turn into a gas forming a cloud known as a coma. Radiation from the Sun pushes dust particles away from the coma and now there is a dust tail. Meantime particles from the Sun convert some of the gases from the comet into ions giving it an ion tail.
NEAT FACT: since the Sun & Solar Wind form the tail of ions, they always point away from the Sun.
Some asteroids are classified on the duration of their orbits, some have orbits that actually take them out of the solar system, some are called Sun-grazers, some are periodic comets that hail from the Kuiper belt, there are main belt comets or lon period comets that hail from the Oort cloud.
Comet 67P/Churyumov-Gerasimenko is a comet with an orbital period of just shy of seven years. Rosetta the ESA spacecraft which launched on March 2nd of 2004 woke up, from its hibernation in January, and in November hopes to land. The comet begins its closest approach to the Sun in August 2015
So dripping already the target comet gets closer to the Sun and as it gets closer the ices bleed off and the comet’s gases emit to with the Sun’s help eventually will turn into a tail. Some of the major “volatiles” in the comet gases include water, carbon monoxide, methanol and ammonia.
The data ‘we’ now possess about the comet comes from observations that were made on June 6 utilizing an instrument called the Microwave Instrument for Rosetta Orbiter (MIRO), and were taken when the spacecraft was about 218,000 miles (350,000 km) away from the comet. MIRO is trying to figure out the make-up of the coma, and will keep following along with the comet as it makes its closest approach to the sun in August 2015. Of course Rosetta will land and get close and personal with the comet deploying a lander called “Philae” where it well check out the surface of the comet.
This an exciting time. Not only do we have Mars on the brain and the Moon in our sights and plan to capture an asteroid but thanks to the ESA the world will witness landing on a comet and achieving data that could be earth shattering.