学进去

Some people will say that you can place a value on anything. We may know the price of milk. We can also find out the value of the most expensive building in the world. Do you think it is possible to put a price on the Earth or other planets?

You probably think this is impossible. Scientist Greg Laughlin thought differently. In March 2009, NASA sent the Kepler telescope (望远镜) into space to explore the Milky Way galaxy and to find Earth-sized planets orbiting (环绕) other stars. As there are billions of stars within the Milky Way, it could mean there were several thousand planets to discover. How could scientists decide which ones to study further and which ones to take no notice of?

Professor Laughlin used information received from the Kepler telescope to create a formula (公式) that puts a price on planets. The age and size of each planet, its temperature, and the energy (能量) it created were considered. Older planets were given a higher value. The most important consideration was whether or not it may be possible for life to live on the planet.

By using his formula, Professor Laughlin found that planet Earth was the most important. He gave it a value of five quadrillion (千的五次幂) dollars. Mars was given a value of US$16,500 and Venus was valued at zero. That’s because it’s impossible to support life on Venus because it is too close to the Sun. The professor said that any planet that had a value of more than US$100 million was worth studying further.

By November 2018, about 1,200 planets in total had been looked at. Most of them were worthless because of their unsatisfactory conditions. So should you run to the bank and borrow US$16,500 so you can buy Mars? Maybe not today. You should just enjoy the five quadrillion dollar planet you already live on — and learn how to look after it.