How Big Are They/ Kuiper belt

3. How Big Are They/ Kuiper belt • The Kuiper Belt is a disk-shaped region past the orbit of Pluto extending roughly from 30 to 50 AU from the Sun containing many small icy bodies. It is now considered to be the source of the short-period comets. • Some astronomers believe that Triton, Pluto and its moon Charon are merely the largest examples of Kuiper Belt objects (Pluto can still be considered a member of the Kuiper Belt in addition to its classification as a "dwarf planet").

4. How Big Are They/ Oort Cloud • The Oort Cloud may account for a significant fraction of the mass of the solar system, perhaps as much or even more than Jupiter. (This is highly speculative, however; we don't know how many comets there are out there nor how big they are.)

6. Our Mission Is • Is to find some samples for earth then sell them and be rich. • And to create a space ship that can stand coldness. To go on the Kupier Belt and Oort could. • And anything you can think of.

8. What is the Kupier Belt and Oort Cloud • This new dwarf planet (see the now out of date "What makes a planet?" below) is the largest object found in orbit around the sun since the discovery of Neptune and its moon Triton in 1846. It is larger than Pluto, discovered in 1930. Like Pluto, the new dwarf planet is a member of the Kuiper belt, a swarm of icy bodies beyond Neptune in orbit around the sun. Until this discovery Pluto was frequently described as "the largest Kuiper belt object" in addition to being a dwarf planet. Pluto is now the second largest Kuiper belt object, while this is the largest currently known.

10. Where it is • The dwarf planet is the most distant object ever seen in orbit around the sun, even more distant than Sedna, the planetoid discovered almost 2 years ago. It is almost 10 billion miles from the sun and more than 3 times more distant than the next closest planet, Pluto and takes more than twice as long to orbit the sun as Pluto.

12. How Big it is • How big is it?Usually when we first discover distant objects in the outer solar system we don't know for sure how large they are. Why not? Because all we see is a dot of light, like the picture at the top of the page. This dot of light is sunlight reflected off the surface of the planet (interestingly the sunlight takes almost a day to get out to the planet, reflect off of it, and get back to the earth!), but we don't know if the object is bright because it is large or if it is bright because it is highly reflective or both. •  When an object is too far away to directly see how big it is, astronomers use an indirect method instead where they measure the heat coming from the object. If we wanted to measure the size of a fire, for example, we could do it by measuring the total amount of heat coming from the fire. The temperature of the flames in a match and a bonfire are essentially the same, but a bonfire emits much more heat because it is much bigger. The same is true of distant planets. Because we know how far away the planet is we have a pretty good idea of the surface temperature (a frosty 405 degrees below zero!), thus when we measure the total heat we can tell how big the object is. Unfortunately, the new planet is so far away and so cold that our first attempt at measuring the heat, using the Spitzer Space Telescope, could not detect the heat output. This fact tells us that the object must be smaller than about 3300 km.

13. How big it is • In the meantime, observations have been made by a group from the University of Bonn from the 30-meter IRAM telescope. This telescope, like Spitzer, measures the heat output. IRAM measures the heat output in a region of the spectrum where much less heat is given off, but IRAM is a much larger telescope than Spitzer. The observations were successful in finally detecting the heat of Eris. From the amount of heat measured they determined that Eris has a diameter of 3000 +/- 400 km.  A very nice discussion of the measurement and what the uncertainties mean can be found  at the press release web page.The newest size measurement comes from  the Hubble Space Telescope. While for most telescopes the planet is too small to be seen as anything other than a dot of light, HST can (just barely) directly measure how big across it is. The measurement is extremely hard, however, even for HST, because even HST distorts light a little bit as it goes through the telescope, and we needed to be sure that we were measuring the actual size of the planet, rather than being fooled by distortion. So we waited until Eris was very close to a star and then snapped a series of 28 pictures and carefully went back and forth comparing the star and the planet. In the end, we determined that Eris t is 2400 +/- 100 km across.

15. Fun Facts • Kuiper belt and Oort cloud is made out of icy comets. • The Oort Cloud is at the end of the sun’s gravitational pull. • The Oort Cloud is a solar system rule breaker because it is not on a flat disk.

16. Question • How big is it? • Where is it? • Is there any Question?

17. Answer • 2400 +/- 100 km across/smaller than about 3300 km. • It is almost 10 billion miles from the sun and more than 3 times more distant than the next closest planet, Pluto and takes more than twice as long to orbit the sun as Pluto.