Telescopes Practice Questions
18 free Telescopes practice questions for the Static GK. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which type of telescope uses a lens as its objective to form an image?
- A Reflecting telescope
- B Refracting telescope
- C Catadioptric telescope
- D Radio telescope
Correct answer: Refracting telescope
Refracting telescopes use a glass lens to gather and focus light. This was the original design used by Galileo Galilei in the early 17th century.
A Newtonian telescope is a specific type of which broader category?
- A Refractor
- B Radio
- C X-ray
- D Reflector
Correct answer: Reflector
The Newtonian telescope is a reflecting telescope that uses a curved primary mirror and a flat diagonal secondary mirror. It was invented by Sir Isaac Newton to solve the problem of chromatic aberration in lenses.
What is the name of the effect where different colors of light are focused at different distances by a lens?
- A Spherical aberration
- B Diffraction
- C Refraction
- D Chromatic aberration
Correct answer: Chromatic aberration
Chromatic aberration occurs because glass bends different wavelengths of light by different amounts. This results in a 'color fringe' around bright objects in simple refracting telescopes.
The Hubble Space Telescope orbits the Earth at an altitude of approximately how many kilometers?
- A 550 km
- B 350 km
- C 2,000 km
- D 36,000 km
Correct answer: 550 km
Hubble orbits in Low Earth Orbit at an altitude of about 547 kilometers. This position above the Earth's atmosphere allows it to take extremely sharp images without atmospheric distortion.
Which of these is the world's largest single-aperture radio telescope, located in China?
- A Arecibo Observatory
- B Very Large Array (VLA)
- C China's FAST Telescope
- D Green Bank Telescope
Correct answer: China's FAST Telescope
FAST, located in Guizhou Province, China, has a diameter of 500 meters. It surpassed the Arecibo Observatory as the world's largest filled-aperture radio telescope in 2016.
What is the primary function of the 'eyepiece' in a telescope?
- A To gather as much light as possible
- B To act as the primary mirror
- C To filter out infrared radiation
- D To magnify the objective's image
Correct answer: To magnify the objective's image
While the objective lens or mirror gathers the light and creates a small image, the eyepiece acts as a magnifying glass for the eye to see that image in detail. Telescopes often come with interchangeable eyepieces for different magnification levels.
Telescopes that use a combination of both mirrors and lenses to form an image are called:
- A Catadioptric
- B Achromatic
- C Interferometric
- D Parabolic
Correct answer: Catadioptric
Catadioptric telescopes, such as the Schmidt-Cassegrain, use both refraction and reflection. This design allows for a long focal length in a very compact tube.
The 'light-gathering power' of a telescope is directly proportional to what?
- A The overall length of the telescope's optical tube
- B The magnification of the eyepiece
- C The weight of the telescope mount
- D The square of the diameter of the objective
Correct answer: The square of the diameter of the objective
Light-gathering power depends on the surface area of the primary lens or mirror. Since area is calculated as $A = \pi r^2$, doubling the diameter increases the light-gathering capacity by four times.
Where is the Chandra X-ray Observatory located?
- A Mauna Kea, Hawaii
- B Atacama Desert, Chile
- C South Pole
- D In Earth orbit
Correct answer: In Earth orbit
X-rays from space are absorbed by Earth's atmosphere, making ground-based X-ray astronomy impossible. The Chandra Observatory must operate in space to observe high-energy regions like black holes and supernova remnants.
Which term describes the process where a telescope's mirror is adjusted in real-time to compensate for atmospheric turbulence?
- A Adaptive Optics
- B Active Optics
- C Atmospheric Correction
- D Interferometry
Correct answer: Adaptive Optics
Adaptive optics uses sensors to measure atmospheric blur and a deformable mirror to cancel out that blur hundreds of times per second. This technology allows ground-based telescopes to achieve clarity comparable to space telescopes.
The Keck Observatory, famous for its twin 10-meter telescopes, is located on which mountain?
- A Mauna Kea
- B Everest
- C Mount Teide
- D Cerro Tololo
Correct answer: Mauna Kea
The W. M. Keck Observatory is located near the summit of Mauna Kea in Hawaii. Its high altitude and dry air make it one of the best sites on Earth for optical and infrared astronomy.
A 'Cassegrain' telescope is distinguished by which design feature?
- A A hole in the center of the primary mirror
- B The use of three different lenses
- C A liquid mercury mirror
- D An eyepiece located at the front of the tube
Correct answer: A hole in the center of the primary mirror
In a Cassegrain design, light reflects off the primary mirror to a secondary mirror, which then sends the light back through a hole in the primary mirror to the eyepiece. This makes the telescope much more compact.
What does the acronym 'VLT' stand for in the context of the European Southern Observatory?
- A Vast Lens Telescope
- B Very Large Telescope
- C Variable Lens Technology
- D Vacuum Laser Telescope
Correct answer: Very Large Telescope
The Very Large Telescope (VLT) consists of four individual telescopes with 8.2-meter mirrors. It is located at the Paranal Observatory in the Atacama Desert of northern Chile.
Which space telescope was launched in 1991 to observe gamma rays?
- A Spitzer
- B Compton
- C Fermi
- D Swift
Correct answer: Compton
The Compton Gamma Ray Observatory was the second of NASA's 'Great Observatories' to be launched. It mapped the sky in high-energy gamma rays until its mission ended in 2000.
Which property of a telescope determines its ability to distinguish two closely spaced objects as separate?
- A Angular magnification
- B Focal length
- C Resolving power
- D Aperture ratio
Correct answer: Resolving power
Resolving power is the ability to see fine detail. It is limited by the diameter of the telescope's aperture; a larger aperture provides better resolution due to reduced diffraction.
The technique of combining signals from multiple telescopes to act as one giant telescope is called:
- A Spectrophotometry
- B Interferometry
- C Photometry
- D Polarimetry
Correct answer: Interferometry
Interferometry uses the interference of light or radio waves from multiple collectors to simulate a much larger aperture. This technique is widely used in radio astronomy to achieve extremely high resolution.
Which of these was the first major space telescope dedicated to finding Earth-sized planets orbiting other stars?
- A Hubble
- B Kepler
- C Gaia
- D TESS
Correct answer: Kepler
The Kepler Space Telescope, launched in 2009, used the transit method to detect thousands of exoplanets. It monitored a specific patch of the Milky Way to determine how frequent Earth-like planets are in our galaxy.
A 'Dobsonian' telescope is a popular amateur design known for what?
- A Its complex electronic tracking
- B Using high-quality lenses for planetary work
- C A simple, low-cost alt-azimuth mount
- D Its ability to fly on high-altitude balloons
Correct answer: A simple, low-cost alt-azimuth mount
Dobsonian telescopes are Newtonian reflectors on a very simple wooden mount. They are designed to be portable and provide the largest possible aperture for the lowest cost.