The first reason is time.Scientists believe the universe is about 12billion years old."This is long enough for other planets to have intelligent life,"say Shostak and Barnett.The second reason is size-the universe is huge."Tools like the Hubble Telescope (哈勃望远镜) have shown that there ...
根据文章第一段中Two far-off planets are likely made of water,according to NASA's research.(根据美国宇航局的研究,两个遥远的行星很可能是由水构成的)以及最后一段中But the new planet described by the researchers,Kepler 138-e,does fall into that just-right area,according to the research.(但是...
The answer probably has to do with planetary size. Venus is roughly the same mass as Earth, and so its upper atmosphere is less extended than that of Mars. That makes it harder for the solar wind to strip away atmospheric gases. Both Venus and Mars do have induced magnetic fields (fields...
1.According to the passage, each of the following statements comparing terrestrial planets with Jovian planets is true EXCEPT: A. Terrestrial planets are closer to the Sun than Jovian planets. B. Terrestrial planets have smaller diameters than Jovian planets. C. Terrestrial planets have smaller ma...
It's the nearest planet to us.B. It's almost the same size as the Earth.C. People can't see it clearly from the outside.D. Anything can't live there.4. Which one is NOT right according to the passage?A. The Earth and Venus are similar in size.B. Both the Earth and Venus ...
A. The Age and Size of the EarthB. Our Galaxy, the Milky WayC. Why Intelligent Life Might ExistD. The Earth: the Only Planet with Intelligent Life ( )3. Why was it hard to look for signs of intelligent life in the universe in the past?
astronomical objects, voted to revoke Pluto’s planetary status and place it under a new classification calleddwarf planet. For a discussion of that action and of the definition ofplanetapproved by the IAU,seeplanet. Understand the relative size of the Sun, the Moon, and other solar system ...
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According to their distance from the Sun, their size, mass and average density as well as their internal structure, the planetary bodies of our solar system can be divided into four major groups (Fig. 32.1, Table 32.1).doi:10.1007/978-3-662-57316-7_32Martin Okrusch...
— The main asteroid belt has lost >99.9% of its solid mass since the time at which the planets were forming, according to models for the protoplanetary nebula. Here we show that the primordial asteroid belt could have been cleared efficiently if much of the original mass accreted to form ...