Who first used a telescope to look at the heavens?
What did Galileo discover when he looked into the heavens through a telescope?
Mountains on the moon, sunspots, and moons orbiting Jupiter.
What is a telescope?
A telescope is an instrument that collects light and brings it to a point, or focus.
What are the three basic components of a telescope?
Objective lens or primary mirror, maginifer, and imaging device.
What does the objective lens or primary mirror do?
Collects and focuses light (the bigger the better).
What does the magnifier do?
Spreads light from the focus onto an imaging device.
What is the magnifier made out of?
It is usually a lens.
What does the imaging device do?
Records the light collected and magnified by the telescope.
What are some examples of an imaging device?
Human eye, film, or electronic chip.
What does an eyepiece do?
Takes the light from the focus, magnifies it, and spreads it out to fill the detectorwfor example, the eye.
What does the tube do?
Holds the two lenses at the correct distances apart and minimizes dust and air currents between the two lenses.
What does the mount do?
Holds and moves the telescope.
What is refraction?
The bending of light as it moves from one medium to another.
When the light first enters the telescope what does the image look like?
It is upside down.
Is the image upside down when it reaches the eye?
Which is better a large objective lens or a small objective lens?
How big is the largest objective lens?
40 inches in diameter.
Who built the first reflecting telescope?
What is reflection?
Process whereby light bounces back from an object at the same angle and intensity that the object received it.
What is the primary mirror?
A long-focal-length mirror that collects and brings the light to a focus.
What does the secondary mirror do?
Deflects the light outside of the tube to the eyepiece.
How big can primary mirrors be?
Big! Greater than 200 inches.
What makes it difficult to bring X rays to a focus?
They have high energy and will penetrate most substances.
How is it possible to use X rays to make a telescope?
If the angle of the incoming X ray is small enough, it will bounce off a mirror (much like skimming a flat stone off the surface of a pond). By placing and angling several small mirrors, you can bring the X rays to a focus for a telescope.
What are the three types of telescopes?
Reflecting, refracting, radio and X ray.
In which telescope would you find an objective lens?
In which telescope(s) would you find a mirror?
Reflecting and X ray.
What are two things that telescopes can make?
Images and spectrograms.
Where do telescopes make images?
On the retina of the eye, on photographic film, or in digital imaging devices.
What is a spectrograph?
A spectroscope (instrument for producing and oberving a spectrum) designed to map and photograph a spectrum.
What is a spectrum?
The distribution of energy given off by a light source such as a star, arranged in order of wavelengths.
What information can a spectrum from a spectrograph give us?
Chemical information about the observed object.
What emits radio waves?
Many stars and other objects in the galaxy.
What are some charactaristics of radio waves?
They can penetrate dust, are transparent in our atmosphere and can be detected easily day or night with a radio telescope.
What is the dish in a radio telescope made out of?
What is interferomety?
When several radio telescopes at various distances apart are electronically linked and act as one large dish.
What are the different kinds of light?
Gamma rays, X rays, ultraviolet light, visible light, infrared and radio.
What are gamma rays?
Cosmic rays emitted by pulsars and neutron stars
What are X rays?
Regions of hot gases, such as star coronas and neutron stars
What is ultraviolet light?
What is visible light?
Stars, planets, galaxies, and nebulae
What is infrared?
Cool stars, planets, star-forming regions, and interstellar dust
What is radio?
Cosmic background radiation, galactic centers, interstellar dust, and cold regions of interstellar clouds
What distorts incoming rays of light and causes blurry images?
The Earth's atmosphere?
What new technology can eliminate much of the blurriness?
What are adaptive optics?
A process that removes distortions (such as those caused by the atmosphere) from a telescopic image in real time
What are the parts of an adaptive-optics system?
A beam splitter, wavefront sensor and wavefront corrector.
What does a beam spltter do?
Splits incoming light to a wavefront sensor and a wavefront corrector.
What does a wavefront sensor do?
Senses the distortion of the light wave hundreds of times each second and feeds that information to the wavefront corrector.
What is usually used as a wavefront sensor?
What does a wavefront corrector do?
Uses hundreds of tiny actuators to deform the surface of the mirror to a shape that cancels the distortions of the incoming wave.
What are the only two types of light that can penetrate the Earth's atmosphere?
Visible light and radio waves.
What happens to X rays, infrared and gamma rays when they hit the Earth's atmosphere?
They get absorbed in the upper layers of the atmosphere.
What is the best and sometimes only way to get multiwavelength images?
Placing telescopes in Earth's orbit.