Mount Wilson Observatory

Scientists use big tools to study the sky.

These tools sit on a tall mountain. The air there is very steady. This helps people see far away.

One big tool is a very large telescope. It was the largest in the world for a long time. It helped a man see that the universe is growing.

Other tools look at the sun. Some tools use tall towers. These towers help the tools stay away from warm ground. This makes the view much clearer.

One tower is very tall. It is 150 feet high. This helps scientists study the sun every day. It is a very busy place for science.

The Mount Wilson Observatory is a special place for science. It sits on a high peak in California. The air there is very steady. This makes it a great spot to study the sky.

This site has many famous telescopes. One is the 60-inch telescope. It was the largest in use when it opened in 1908.

It used a glass mirror to see the stars.

The Hooker telescope is even larger. It was completed in 1917. It was the world's largest telescope until 1949.

A man named Edwin Hubble used it. He proved that the universe is expanding. He also showed that other galaxies exist outside our own.

Some tools at the site look at the sun. Scientists use solar telescopes for this work. One is a very tall tower. It is 150 feet high.

The tower design keeps the tools away from warm ground. This helps the view stay clear. The observatory is still a busy place for research today.

The Mount Wilson Observatory is a famous place for studying space. It sits on Mount Wilson in Los Angeles County, California. This peak is part of the San Gabriel Mountains. The location is perfect for looking at stars. An inversion layer traps warm air and smog over Los Angeles. This creates very steady air on the mountain. Steady air helps scientists see much clearer images of the sky.

Many different telescopes work at this site. Some tools look at the Sun using solar telescopes. The Snow solar telescope was the first one installed there. It was the first solar telescope that stayed in one place. Other tools use tall towers to look at the Sun. The 60-foot Solar Tower was built to see better images. It sits high above the ground to avoid heat distortion. The 150-foot Solar Tower uses a special design. It has an inner tower and an outer tower. This design keeps the tools from swaying in the wind.

George Ellery Hale was the person who founded the observatory. He had built a large telescope at the Yerkes Observatory before this. The Carnegie Institution of Washington provided the first funding in 1904. They leased the land from the owners of a local hotel. In the 1880s, Edward Falles Spence tried to start this project. However, he died before he could finish raising the money. Building the telescopes was a very hard job. For example, the 60-inch telescope parts had to be moved up the mountain.

History shows how these tools changed what we know. The 60-inch telescope was completed in 1908. It was the largest operational telescope in the world at that time. Then came the 100-inch Hooker telescope in 1917. This massive tool was the world's largest until 1949. Edwin Hubble used the Hooker telescope to make huge discoveries. In 1923, he proved that the Andromeda nebula is a galaxy. He also showed that the entire universe is expanding.

Today, the observatory is still a very busy center for science. Light pollution from the growing city of Los Angeles is a problem. This bright light makes it hard to see deep space. However, the CHARA array is still doing important research. This array became fully operational in 2004. It was the largest optical interferometer in the world when it was finished. Many people can still visit the 60-inch telescope. It is the second largest telescope in the world for the public.

The Mount Wilson Observatory (MWO) is a major astronomical research center. It is located on Mount Wilson in Los Angeles County, California. This peak sits within the San Gabriel Mountains. The site is famous for its unique atmospheric conditions. An inversion layer traps warm air and smog over the Los Angeles basin. This process leaves the mountain with steadier air than most other locations in North America. Steady air is essential for high-quality astronomy. It is especially helpful for a technique called interferometry, which combines light from multiple sources.

The observatory has hosted several groundbreaking telescopes. The 60-inch telescope was the largest operational telescope when it finished in 1908. Later, the 100-inch Hooker telescope became the world's largest from 1917 until 1949. The site also features specialized solar telescopes. These include the Snow solar telescope, the 60-foot Solar Tower, and the 150-foot Solar Tower. More recently, the CHARA array was completed in 2004. At its completion, the CHARA array was the largest optical interferometer in the world. It continues to perform important stellar research today.

Solar research at Mount Wilson relies on specific tower designs. The 60-foot Solar Tower was built to achieve high resolution. It placed the optics high above the ground to avoid distortion. This distortion is caused by the Sun heating the Earth's surface. The 150-foot Solar Tower uses a more complex "tower-in-a-tower" design. An inner tower supports the optical instruments. An outer tower surrounds the inner one to support the dome and floors. This structure isolates the optics from wind. This prevents the wind from swaying the tower and blurring the images.

The history of the observatory began with early efforts in the 1880s. Edward Falles Spence attempted to fund a telescope project. However, he died before the funding was complete. George Ellery Hale eventually conceived and founded the observatory. Hale had previously built the 1-meter telescope at Yerkes Observatory. In 1904, the Carnegie Institution of Washington provided the first funding. They leased the land from the owners of the Mount Wilson Hotel. The lease required that the observatory allow public access.

Many scientific milestones occurred using these instruments. In 1908, Hale used the 60-foot tower to record Zeeman splitting. This proved that magnetic fields exist outside of Earth. In the 1960s, Robert Leighton discovered a 5-minute oscillation in the Sun. This discovery started the field of helioseismology. The 100-inch Hooker telescope changed our understanding of the cosmos. In 1923, Edwin Hubble proved the Andromeda nebula was a separate galaxy. He used a Cepheid variable star to calculate its distance. In 1929, Hubble and Milton Humason confirmed the universe is expanding.

The 60-inch telescope also led to major discoveries. It allowed for spectroscopic analysis and nebula photography. In 1992, it received an adaptive optics system called ACE. This system was developed by DARPA for the Strategic Defense Initiative. The National Science Foundation funded its use for civilian science. This system improved the telescope's resolving power significantly. It went from 0.5 to 0.07 arc seconds. Today, the 60-inch telescope is the second largest telescope in the world dedicated to the public. People can book it to view the Moon and planets.

Despite its success, the observatory faces modern challenges. The growth of the Los Angeles area has increased light pollution. This bright light makes deep space astronomy much more difficult. However, the observatory remains a productive scientific center. The CHARA array provides a way to continue studying stars. The site connects historical discovery with modern technology. It remains a vital link in the history of how we see the universe.