Date: 12-14-00
SCIENCE REPORT - Observing Venus
By Mario RitterThis is the VOA Special English Science Report.
This month there will be a sight in the evening sky worth seeing. Look to the west after the sun has set and the sky has darkened. The brightest "star" in the sky is not a star at all, but a planet. The planet Venus is the brightest object in the sky after the sun and moon. It will shine very brightly in the west after sunset for the rest of the year.
On December twenty-ninth the moon will be very close to Venus. The moon will not appear round, but it will have what is called a crescent shape. Surprisingly, Venus too can appear to have a crescent shape if you look at it through a telescope. Even a small telescope will show that Venus is not a point of light at all but round like the moon. During December, Venus will be only about half lit by the sun.
Venus is very similar to the Earth in size. The substances that make up the two planets are also very similar. However, Venus has a very different atmosphere than the Earth does. The atmosphere of Venus is mostly made up of the gas carbon dioxide. Most space scientists believe that the gases in the atmosphere of Venus trap heat from the sun. Scientists call this process the "greenhouse effect" because energy from the sun is trapped in the atmosphere of a planet. Heat is trapped in a greenhouse, a glass house where plants are grown, in a similar way.
On Venus, the atmosphere is very thick so it traps much of the energy from the sun. This trapped energy causes the temperature on the surface to be very high. The average surface temperature of Venus is about four-hundred-sixty degrees Celsius.
The atmosphere of the Earth is mostly made up of the gases nitrogen and oxygen. Carbon dioxide makes up a very small part of Earth's atmosphere. But some scientists say that a "greenhouse effect" is possible on Earth. Tom Wrigley is a scientist for the National Center for Atmospheric Research. He has done studies that appear to show that the amount of carbon dioxide in the Earth's atmosphere has increased. Other studies appear to show that the Earth's average temperature has increased by one degree Celsius.
Venus is the best example of what could happen to the Earth if carbon dioxide gas causes the "greenhouse effect."
This VOA Special English Science Report was written by Mario Ritter.
Source: www.voa.gov/special/