Earth, and more planets with life: how life begins, where it may go

Earlier this month, astronomers monitoring the data from the Kepler satellite observatory, which has been orbiting the sun since being launched from Cape Canaveral in 2009, released a list of 400 stars that are most likely to be able to nurture life on the planets within their solar systems. Referred to as being in the “Goldilocks” zones (not too cold, not too hot, but just right to hold liquid water), these are the planets with ideal conditions to support life.

How can the astronomers working on the Kepler project know what to look for when searching for signs of the capacity for life through their $600 million satellite observatory? It helped to figure out what created the conditions for life on our own planet.

Here’s how scientists figure it went for planet Earth: About 4.5 billion years ago, our sun was slowly collapsing via the force of gravity. Because of the great pressure created by gravity the sun became extremely hot. Its temperature rose to millions of degrees centigrade. The sun’s gravity had sucked in a tremendous amount of material and finally caused a gigantic explosion to occur.

The sun violently expanded to many times its original size, and the explosion sent its matter hurtling at enormous speeds in every direction and in all sizes and speeds. Both gases and molten solids from the size of small particles to the size of giant planets were driven off into space. Some of it was hurled off at such a great velocity that it never was able to return to the sun.

After this initial explosion, the sun, which had been rapidly expanding, started to cool. The expansion of the sun ultimately came to a halt. When this expansion stopped altogether, the sun then began to contract. After a time of contraction the sun again expanded and exploded with tremendous force. That sent a great deal more matter into space.

However, the force of the explosion this time was not as strong as the first one. The pulsation of the sun gradually diminished over millions of Earth years. Eventually, out of all this chaos and turmoil, our own solar system began to emerge. The Earth was 93 million miles from the sun, the right distance to be able to receive warmth from the sun without damage to its surface.

The sun began to emit a regular amount of radiant energy. This made the existence of life on Earth possible. At this time, solar flares would throw globs of matter and gases into space, and some of these became comets. For the most part, these materials receded back to the sun. Eventually out of all this chaos and turmoil our solar system began to emerge. Remember that this was all happening some millions of years ago.

As the forming Earth had gases and water and elements, it began to set up life in the form of miniature bugs and the like. Life necessarily required proper temperatures, and the position of the Earth with respect to the sun enabled that to exist.

Other masses exploded out of the sun and found their ways of circling the sun and at different distances from it. These are the planets that now exist in the solar system.

The closest planets to the sun are Mercury and Venus. Their closeness causes the temperatures on these two planets to be extremely high, making it impossible for life to exist on them.

The other planets that circle the sun are farther away and receive very little temperature from the sun, remaining extremely cold and unable to sustain life. These are Mars and then Jupiter, the largest planet in the solar system, and then Saturn, Uranus and Neptune.

By 10,000 B.C. there were probably about 10 million people on Earth. These people existed all over the planet. And their numbers continued to grow year by year. It took many years, and by 1800 we had reached 1 billion humans living on Earth.

Of course, human life continued to increase, and in only 25 years, from 1974 to 1979, the world population grew from 4 billion to 6 billion people. At the present time, there are about 6.8 billion people living on Earth, and the number continues to grow.

Water is the most important necessity for maintaining life on Earth. More than 80 percent of the Southern Hemisphere and 61 percent of the Northern Hemisphere is covered with water. Of the entire planet, 70 percent is covered by water but only 1 percent is what we know as fresh water. The amount of precipitation that falls on the Earth annually is more than 13 quintillion gallons. And it is this water that is necessary to maintain life on our planet.

Astronomers and scientists are thinking about how and when the Earth will lose its inhabitants and they have a variety of opinions. Some believe that the Earth will explode in 1 billion years. Some think that the Earth will go on with life on it for 2 or 3 billion more years. Some believe that the sun will continue to heat up and within 1 billion or less years will cause the Earth to become totally uninhabitable.

If you look at all of the various beliefs, you have to decide that the Earth will last at least one-half-billion to 1 billion years, and perhaps a lot longer, supporting its people on it. When we think about a person’s life as being from 50 to 100 years, these ideas of the scientists are really tremendous.

When the life on our planet diminishes, the people are likely to be the first to die and leave behind microbes and similar living things. The sun is likely to get so hot that it explodes and takes all of its planets off into space, including our Earth.

What is OK about all this is that the time is so long that our children, grandchildren,and more will just continue to grow up on Earth and find interesting things to do. Wouldn’t it be fun to be reborn a half-billion years from now, on Earth or on one of the Goldilocks planets yet to be discovered, and to do whatever work we enjoy doing?

Sidney X. Shore is a scientist, inventor and educator who lives in Salisbury and holds more than 30 U.S. patents.

The wish of Sid Shore that all Lakeville Journal readers continue to explore the galaxies in their own backyards, as well as throughout the wide world. His message while writing about 60 columns for this newspaper has been that all of us should expand our creativity and potential at every stage of our lives.

Thank you, Sid, for such positive and inspiring words.

— The Editor