In our solar system, the search for extraterrestrial life forms continues. The United States as well as the Soviet Union has sent numerous unmanned space probes to flyby, orbit, or soft land on all of the planets and larger moons in our solar system yet no life forms of any kind have been found. In addition, twelve American astronauts have walked on and studied the lunar surface, but were also unable to find any extraterrestrial life.
It is very doubtful that any life forms beyond simple plant or microbial life will be discovered in our solar system. We will have to look outside our solar system for any higher order intelligent life.
The speed of light is 186,282 miles per second. At this speed, you could travel almost 7.5 times around the Earth’s equator in one second. Yet at this speed, it would take almost 4.3 years to reach the next nearest star system outside of our Sun which is called Alpha Centauri. There are very few star systems less than 10 light years away.
In order for us, or any alien civilization to perform interstellar travel, that is to travel from one star system to another, would be an extremely difficult task. To escape the Earth’s gravity field, the rocket you are traveling in must reach a speed of at least 25,000 miles an hour. Yet at this tremendous speed, it would take your rocket nearly 26,825 years to reach a star system only one light year away. Therefore, to reach the Alpha Centauri star system would take about 115,347 years. This is a very long time indeed.
In order to travel at fast speeds in your rocket, it would require an enormous amount of fuel making your spacecraft extremely heavy indeed. Other ways to negotiate interstellar travel would be to put the passengers in some form of suspended animation to slow down their aging process considerably.
Another method would be to send a colony of passengers to journey to another star system. However, the original passengers on this voyage would never see this new world but, perhaps, their great-great grandchildren might. However, what effects would occur to these passengers during this arduous journey?
Just imagine, however, if some alien civilization would be able to conquer interstellar travel. Their technology would be extremely advanced in starship propulsion systems. It would also be logical to assume that if they were that advanced in interstellar travel, then they are more than likely equally advanced in many other disciplines such as in the field of medicine where they have found cures for many diseases.
Our Sun is a star. Around every star system there exists a region called the habitable zone where liquid water can exist to support life as we know it. In our solar system, the habitable zone is from the planet Venus to Mars, the second and fourth planets in order of their distance from the Sun. The Earth is the third planet.
Around many stars in our galaxy, the Milky Way, astronomers have found planets orbiting around them. These planets orbiting around other star systems are called exoplanets. Many of these exoplanets lie within the habitable zone, and could, therefore support intelligent life forms.
Whenever you look up in the night sky to view a celestial object you are actually looking backward in time. The Moon, on the average, is approximately 239,000 miles away. Therefore, it takes light from our Moon to reach our eyes on Earth about 1.28 seconds. For the Planet Jupiter, it would take light about 43 minutes and 13 seconds to reach a viewer on Earth.
If you look at the star Rigel , the brightest star in the constellation of Orion, the Hunter, you are actually seeing this star as it appeared 900 years ago, and not how it appears today because it is 900 light years away.
Astronomers hope to someday communicate with an alien civilization, but this too is a very difficult task. If you were able to communicate with intelligent beings from the Rigel star system, it would take a total of 1800 years to send a message to them, and receive a response back if they answered immediately.
In March, 1972, the United States launched an unmanned mission to flyby and study the planet Jupiter. The spacecraft was known as Pioneer 10. Afterwards, it would continue to fly out beyond our solar system. A similar unmanned spacecraft named Pioneer 11, launched in April, 1973, flew by Jupiter, and then the ringed planet Saturn.
A plaque was carried aboard each Pioneer spacecraft in the event that it was eventually found by extraterrestrial intelligent life forms. The plaque contained a drawing of a man and a women as well as a drawing of where our solar system was located in our galaxy.
In 1977, the U. S. launched two unmanned spacecraft called Voyagers 1 and 2. The twin spacecraft were to flyby and explore the same two planets Jupiter and Saturn. After studying these two planets, Voyager 1 continued to travel beyond our solar system, and into interstellar space. The spacecraft is now more than 11 billion miles from the Earth.
Voyager 2, after studying Jupiter and Saturn as well, flew by the planet Uranus in 1986, and Neptune in 1989. This spacecraft is also now leaving the confines of our solar system.
Aboard both Voyager spacecraft are two hours of Earth sounds, digital photos, and a message from the President of the United States. It was hoped that these two spacecraft might encounter some intelligent life forms on their journey, and inform them of our Earthly presence.