Visible light astronomy includes a variety of observations with optical telescopes that work with visible spectrums of light. Visible light is part of the electromagnetic spectrum of light emitted from frequencies of electromagnetic radiation. Light has properties such as photo energy, wavelength and frequency. The electromagnetic spectrum includes a variety of different frequencies such as visible light, gamma rays, ultraviolet, infrared, microwaves radar, and radio waves, just to name a few. Electromagnetic radiation interacts with matter differently throughout the spectrum of light.
Visible light astronomy has been around since human beings first noticed the night sky thousands of years ago. Early man has minimal recorded information, but there is something to look back on. There are drawings in caves of comets, supernovae, stars, eclipses, and more. Observations were made with the naked eye, but visual light astronomy would soon transform, and make a big impact on people.
In 1600 B.C. Babylonian people recorded positions of planets, and times of eclipses. The ancient Greeks took this information and continued to expand on their knowledge of the stars. They used data to predict times of eclipses. Hipparchus created the first star catalog in 100 B.C., which is now known as the constellations. From there people began to create more detailed pictures and models of the solar system. The first telescope was created in the 17th century by craftsman and scientists who are not named. The methods used to make lenses were already known because people had eyeglasses since the 13th century. The tools were available to build telescopes in the 13th century, but man did not officially invent the telescope until the 17th century.
Telescopes and Collecting Data
Optical telescopes are telescopes that most people are able to use at home on their own. These standard telescopes allow anyone to view the stars as long as other conditions are right. Refractors are optical telescopes that use lenses similar to what you might find in binoculars or eyeglasses. The lens collects and focuses the light coming from the stars to give you a closer view of the details. Reflecting telescopes also fall within the optical telescope range. These telescopes use mirrors to focus light and make it more visible.
The Hubble Space telescope has more advanced capabilities when compared with a typical optical telescope. This very large telescope resides in space above the Earth. The Hubble Space telescope is about 354 miles above the Earth. The telescope cost more than 2.5 billion dollars to create. For two decades the Hubble has captured some of the most amazing images of distant galaxies, and other objects such as the Crab nebula, Eagle Nebula, and deep field images of ancient galaxies.
Hubble has uncovered some of the greatest images known to man, but Kepler is another telescope with a different mission. Kepler has the capabilities to uncover amazing images of galaxies, but this telescope has a very different primary focus. Kepler collects data and images of stars, and planets circling these stars. Kepler seeks out points of darkness that occur as a planet orbits its parent star. Kepler can detect the mass of the star and planet. The mission is to find other alien planets or Earth-like planets in the universe.
- Hubble: Picture of the Day
- New York Times: Hubble Space Telescope
- BBC News: Hubble Space Telescope Achieves Deepest Cosmic View Yet
- Exploratorium: Hubble Images and More
- Space Telescopes: Kepler Latest News
Effects of Light Pollution
Light pollution does have an effect on visible light astronomy because it can interfere with the brightness of stars, and it creates a haze in the sky. Light pollution is often seen as an orange glow that is seen around cities and suburbs. This light pollution affects visibility, but it can also affect the rhythm of plants and animals that live too close to populated areas. Unshielded lights send light in all directions and this makes it harder to see the full view of the night sky. This is why many space observatories are found in the middle of the desert or other remote places. The area needs to be dark and nearly free of light pollution, so astronomers can get the best picture of the night sky. Amateur astronomers living in unpopulated areas can still get a pretty good view of the stars, but the best view is seen in the darkest places, far from civilization.
- IDA: Light Pollution Effects on Wildlife
- PMC: Health Effects of Light Pollution
- Light Pollution and Astronomy
Future of Visible Light Astronomy
The future of visible light astronomy is very bright. We have only begun to peer into the cosmos, and new discoveries are made all the time by astronomers viewing the night sky. People are likely to continue to use, and build optical telescopes. Radio astronomy is also likely to become more popular as knowledge continues to expand. People may also gain access to more advanced telescopes, allowing them to view the stars at an even deeper level.