Infrared astronomy

Some light is invisible to our eyes.

Scientists use special tools to see it. These tools look for heat light.

This light comes from many things. It comes from the moon and stars. It even comes from dust in space.

Water in the air can block this light. Because of this, many tools go to high places. Some go to dry mountains.

Other tools fly in space. The James Webb Space Telescope is one.

These tools help us see the stars.

They can find new stars being born. They even find water in space. It is a wonderful way to see the sky.

Some light is invisible to our eyes. Scientists use special tools to see it. They look for infrared light. This is a type of light that comes from heat.

William Herschel first found this light in the year 1800. He used a prism and a thermometer. He saw that heat was highest just beyond red light. Today, we use infrared light to study the stars. It helps us see through space dust. This dust can block regular light. But the dust lets infrared light pass through.

It can be hard to see this light from Earth. Water vapor in our air absorbs it. To fix this, we put telescopes in dry, high places. Some telescopes even fly in planes.

Others go into space. The James Webb Space Telescope is a famous one. Space telescopes do not have to deal with Earth's air. They can see things like new stars and water in space.

Infrared astronomy is a special way to study the universe. Astronomers use infrared radiation to look at objects in space. This light has wavelengths between 0.75 and 300 micrometers. It sits between visible light and submillimeter waves.

Visible light is what our eyes can see. Infrared light is invisible to us, but it carries amazing information. It helps us see things that regular light cannot show. For example, it can reveal distant quasars. It can also help us see through thick clouds of dust.

This work happens by catching heat energy. Many objects in space emit thermal energy as infrared light. To see this, telescopes must be very cold. They use coolants like liquid nitrogen to stay chilled. If they were warm, the telescope's own heat would block the view.

Some telescopes use special tools called detectors. One common type is the HgCdTe array. These tools catch the light and turn it into data. This allows scientists to map out star clusters and nebulae.

People have been studying this light for a long time. William Herschel discovered infrared light in the year 1800. He used a prism and thermometers to find it. He noticed the temperature rose highest just past the red color. He called these "calorific rays." Later, Charles Piazzi Smyth detected radiation from the Moon in 1856. Ernest Fox Nichols also tried to see stars like Arcturus. He is often credited with the first star detection.

Modern infrared astronomy grew quickly after the 1960s. This happened because radio astronomy became very successful. Scientists realized there was so much more to see. Many important space missions have since been launched. The IRAS mission made a survey of the whole sky in 1983. The European Space Agency launched the Infrared Space Observatory in 1995. It found water on Saturn and Uranus.

NASA also launched the Spitzer Space Telescope in 2003.

It can be hard to see infrared from the ground. Water vapor in our air absorbs much of this light. To solve this, we build telescopes in high, dry places. The Atacama Large Millimeter Array sits on a high plateau.

Other observatories are in the Antarctic or on Mauna Kea. Some telescopes even fly in airplanes to get above the clouds. The best place is space. The James Webb Space Telescope stays in space to see clearly. This allows us to see the very first stars and galaxies.

Infrared astronomy is a specialized branch of astronomy. It focuses on observing and analyzing objects in space using infrared radiation. This radiation has wavelengths ranging from 0.75 to 300 micrometers. This specific range sits between visible light and submillimeter waves.

By studying this light, astronomers can see features of the universe that are invisible to the naked eye. This includes seeing through cosmic dust and observing extremely distant objects.

To understand how this works, we must look at how heat and light interact. Many celestial objects emit thermal energy. This energy is released as infrared radiation. Because of this, infrared telescopes must be kept extremely cold. They often use coolants like liquid nitrogen to stay chilled. If the telescope itself were warm, its own heat would create "noise." This noise would be much stronger than the faint signals from space.

Detectors like HgCdTe arrays are used to capture this light. These arrays work well for wavelengths between 0.6 and 5 micrometers.

Infrared light can be divided into several distinct regions. The near-infrared region has wavelengths just longer than visible light. Because it behaves similarly to visible light, it is often included in the "optical" spectrum. Many optical telescopes, such as those at Keck Observatory, can also see in this range. The mid-infrared covers different wavelengths used by dedicated instruments. Finally, the far-infrared extends all the way to submillimeter wavelengths. Telescopes like the James Clerk Maxwell Telescope observe these much longer waves.

The history of this field began with a famous experiment. In 1800, William Herschel discovered infrared radiation. He used a prism to split sunlight into different colors. He placed thermometers in the light to measure temperature changes. He found the highest temperature increase occurred just beyond the red color. He called these invisible rays "calorific rays." Later, in 1856, Charles Piazzi Smyth detected radiation from the Moon. Ernest Fox Nichols is also credited with the first detection of a star in infrared. Modern infrared astronomy truly began after the 1960s. This growth followed the success of radio astronomy.

Space missions have provided massive amounts of data. In 1983, the IRAS mission performed an all-sky survey. The European Space Agency launched the Infrared Space Observatory in 1995. Before it ran out of liquid helium in 1998, it discovered water on Saturn and Uranus. NASA launched the Spitzer Space Telescope in 2003. Spitzer discovered the Double Helix Nebula and light from extrasolar planets. Today, the James Webb Space Telescope continues this work from space.

Infrared astronomy is vital for seeing through the obstacles of space. Intergalactic dust can greatly dim the light of distant galaxies. This dust absorbs visible light and re-emits it as infrared light. Because of this, galaxies are actually almost twice as bright as they appear in optical views.

Infrared light also helps us study quasars. These objects move away from Earth, causing a large redshift. This makes them very difficult to see with standard optical telescopes. Infrared tools provide much more information about these distant targets.

Observing from Earth presents a major challenge. Water vapor in our atmosphere absorbs a lot of infrared radiation. To fix this, astronomers build telescopes in very high and dry places. Examples include the Atacama Large Millimeter Array on a high plateau.

Other sites include Mauna Kea and the Antarctic. Some scientists even use airborne observatories like SOFIA to fly above the atmosphere. However, space remains the ideal location. Space telescopes avoid atmospheric blurring and absorption entirely. This allows for the clearest possible view of the cosmos.