to: The Discovery of Uranus, The
Voyager 2, The Future
THE DISCOVERY OF
Uranus was discovered in 1781.
Before that, our solar system consisted of just six planets: Mercury,
Venus, Earth, Mars, Jupiter and Saturn. William Herschel, a German
musician in England believed that the sky was full of secrets. He began
to build his own telescope in his free time. After some two hundred
failures, he finally produced a working telescope with a 6.5 inch
reflecting mirror that showed clear images. On March 13, 1781, Herschel
looked at the constellation of Gemini and saw that it was large and pale
blue in color. This suggested to him that it was a lot closer to Earth
than anyone had imagined and actually not part of Gemini at all.
Thinking that he had found a planet, he began to record its movements.
Soon, he realized that the behavior of this object was not like an
ordinary comet. He realized that he had discovered a new planet-the
seventh planet orbiting the sun. During Herschel's work, King George III
encouraged and rewarded him. To show his gratitude, Herschel wanted to
call this new planet George's Star. It was later changed to Uranus after
the Greek god of the heavens to match the other planets that are named
after Greek and Roman gods. These names follow in ancestral order, where
Mars is the son of Jupiter, Jupiter is the son of Saturn and Saturn is
the son of Uranus.
picture of Uranus was taken by the Voyager 2. The one on the
left is a true-color image, while the one on the right is a
false-colored image of Uranus.
THE VOYAGER 2:
Most of the information of
Uranus was sent back to us by Voyager 2, the U.S. space probe. It took
pictures and measurements of our solar system for years and sent them
back to Earth by radio waves. The Voyager 2 was launched in August of
1977 and actually put on a course for Jupiter. The mission was for it to
survey that planet two years later. The next target was Saturn, which in
August of 1981, the Voyager sent back pictures of Saturn and its rings.
Since the probe was still functioning very well, scientists sent it out
There were several problems to fix
before the scientists could get the probe to Uranus. First was the great
distance. Uranus was about 1.84 billion miles away, making it take 2
hours and 45 minutes for radio messages to travel between Earth and the
Voyager. Instructions for the probe had to be sent out 2 hours and 45
minutes in advance. Another problem was that since the sunlight was so
dim around Uranus, snapshots could not be taken. Long exposures were
needed for the Voyager to bring back information. The problem was that
the Voyager moved about 100 miles during a ten second exposure making it
difficult to get a clear picture. The engineers programmed the Voyager
so that it moved slightly backward to offset its motion forward. The
effect was that the camera was able to remain on target and take clear
The Voyager 2 will continue to
travel further and further away from Earth until it reaches deep space.
But even then, it will still send back pictures of everything it sees
In the first two hundred years
after Uranus was discovered, we learned very little about this planet.
It was too far away to be observed in great detail from Earth. It all
changed in 1984 when Voyager 2 gathered enough information to increase
our knowledge of Uranus. Before the Voyager was launched, the scientists
had planned to send a whole series of space probes to explore the
planets. They wanted to take advantage of the position of the planets
since they were all aligned on the same side of the sun. This is a rare
occurrence and would not happen again for the next 175 years. This
mission was called the Grand Tour. Due to a cut on the funds, only two
probes were sent to study Jupiter and Saturn. Because the information
that was sent back to us was so valuable, the scientists were allowed to
reprogram the Voyager so it could fly by Uranus and Neptune. The probe
used the gravity of the planet that it passes to go out further at a
greater speed to reach the next planet. It took eight and a half years
for the Voyager to travel from Earth to Uranus. Without the planets
gravitational assist, it would have taken some thirty years.
listen to messages that the Voyager sends back as it searches for the
point where the solar winds die and charged ions no longer travel away
from the sun but instead towards it. This is the edge of our solar
system. A lack of funds continues to force the space program to move
slowly. No new probes were planned for Uranus in this past century.
Uranus will remain a mystery two billion miles away.