--------- #1315 - How Do Asteroids and Planets Evolve?
- Attachment: An asteroid.
- Astronomers have discovered over 1,200 planets orbiting other suns to date. Most that have been studied so far turn out to be very unfriendly worlds, nothing like our Mother Earth.
- One of these planets is orbiting a powerful X-ray Source. Its orbit is only 3,000,000 miles away from its powerful sun. Our Sun is 93,000,000 miles away. It too is a powerful Gamma Ray and X-ray source but only at the core of the Sun. By the time the more powerful photons have traveled from the core to the surface they have lost so much energy that they leave the surface as heat and light. That is infrared radiation and light radiation. Of course, there are flares and sunspots that at times emit more powerful radiation, but, most of the time our Sun gives us friendly warmth and light by the time it reaches the surface of Earth.
- This is not the case with planet, CoRoT-2b, where its surface is heated to 1,500 degrees Kelvin from its powerful sun. Our Earth surface has an average temperature of 300 degrees Kelvin. This enormous heat on CoRoT-2b is causing the surface of the planet to evaporate. In fact 50% of the planets mass is now in its atmosphere. The solar wind from its powerful sun is blowing away 5 million tons of its atmosphere every second. The question is, how long can this planet last with its atmosphere. The answer may surprise you.
Let’s do the math:
- The exoplanet is 880 lightyears from Earth. It orbits its star once every 1.7 days ( versus our 365 days). The planet is large, 3 times the mass of the planet Jupiter. Jupiter’s mass is 1.9*10^27 kilograms. Jupiter is 315 times bigger than Earth which is 5.97*10^24 kilograms mass. If this planet is 3 times Jupiter’s mass it is 5.7*10^27 kilograms.
- If the planet’s atmosphere is 50% the mass of the planet then the mass of the atmosphere is 2.9*10^27 kilograms.
- If the sun is so hot and emitting so much radiation that the planet is loosing 5 million metric tons every second it must have a limited amount of time before all the atmosphere is blown off into outer space. 5 million metric tons is 5*10^9 kilograms ( 1 metric ton is 1,000 kilograms).
- If it is loosing 5*10^9 kilograms every second than each year which is 3.1*10^7 seconds it is loosing 15.5*10^16 kilograms /year.
- Since the mass of the atmosphere is 2.9^10^27 kilograms it would take 1.8*10^10 years to loose all of its atmosphere. That is 18 billion years. Our planet has only lived for 4.5 billion years. Our Sun is only expected to live for 10 billion years. So, this exo-planet that is getting blasted by powerful X-ray radiation will outlive the source that is producing the radiation. So, the surprise is that the planet will likely outlive its star.
- The asteroids that are orbiting our Sun are the rocky debris that our four inner planets are made of. Recently a pair of asteroids were discovered orbiting each other as they orbit the Sun together. It is not as if a bigger asteroid has a smaller moon. These two asteroids are the same size, one 55 miles diameter and the other 52 miles diameter. The distance between them as they swing around their common center of gravity is only 53 miles.
- The theory for how this odd pair were created is that a larger asteroid received a grazing collision that sent it spinning very rapidly. The Centrifugal Force of the rapid spinning split the asteroid in half. The two halves of the same material are still orbiting each other every 16 ½ hours. Together they orbit the Sun every 5.6 years. We have learned much of this data because through part of the orbit about the Sun from our viewpoint the two are eclipsing each other. That is how we have learned their shape and mass.
- The volume to mass tells us these asteroids have very low densities, only 1.3 grams per cubic centimeter. That is slightly more dense than water ice. At the same time their surface is so dark, pitch-black, that it only reflects 6% of the sunlight that hits it.
- When a Japanese spacecraft visited an asteroid called Itokawa it collected some material from the surface and returned it to Earth for study. The discovery was that the asteroid material is the same as the chondrite meteorites that we find on Earth.
- The spacecraft was launched in 2003, landed on the asteroid in November 2005. The asteroid was 3/10 of a mile in diameter and 186,000,000 miles away. It collected grains of material off the surface and headed home. The spacecraft landed in Southern Australia in June, 2010, with 1,500 grains of asteroid dust. Most of the grains were only 0.1 millimeter in size.
- After a year studying these grains what have we learned:
--------------- The meteorites scattered across our globe are the same material. They were all formed together in the early solar system evolution about the same time.
------------- Data from electron microscopes and X-ray diffraction measurements showed signs of impact shocks and heating up to 800 C. Evidence indicating the material was deep inside the asteroid which means the asteroid was bigger at one time. It was about 12 miles diameter before it suffered the severe impacts. It is 3/10 of a mile diameter today.
------------- Isotope ratios and element proportions again confirmed that Earth’s chondrite meteorites were once part of asteroids.
-------------- Noble gas isotopes indicate that there is irradiation form solar winds and cosmic rays. The radiation caused the asteroid to continuously loose its surface material at the rate of 10’s of centimeters every billion years.
--------------- The evolution of asteroids and planets is coming to light with discoveries every day. We all came down the same path together in the evolution of the Universe. The strange results give us mysteries to ponder. Our pondering is the strangest of all. An announcement will be made shortly, stay tuned.
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707-536-3272, Friday, October 28, 2011
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