Astronomy Exam: Telescopes

Which type of telescope uses a lens to gather and focus light?

• Reflector

• Refractor

• Catadioptric

• Radio

Answer explanation

A refractor telescope uses lenses to gather and focus light, making it ideal for viewing celestial objects. In contrast, reflector telescopes use mirrors, catadioptric combines both, and radio telescopes detect radio waves.

What is the primary purpose of a telescope's aperture?

• To magnify the image

• To gather light

• To reduce chromatic aberration

• To stabilize the image

Answer explanation

The primary purpose of a telescope's aperture is to gather light. A larger aperture allows more light to enter, improving image brightness and clarity, which is essential for observing distant celestial objects.

Which of the following is a disadvantage of refractor telescopes?

• They are prone to chromatic aberration.

• They are difficult to align.

• They are less portable.

• They have a narrow field of view.

Answer explanation

Refractor telescopes are prone to chromatic aberration, which causes colors to blur and distort due to the different wavelengths of light being focused at different points. This is a significant disadvantage compared to other telescope types.

What is the focal ratio of a telescope with a focal length of 1000mm and an aperture of 200mm?

• f/5

• f/10

• f/20

• f/50

Answer explanation

The focal ratio (f-stop) is calculated by dividing the focal length by the aperture. Here, 1000mm / 200mm = 5, so the focal ratio is f/5, which is the correct choice.

Which type of mount allows a telescope to follow the rotation of the sky by aligning with the Earth's axis?

• Alt-Azimuth

• Equatorial

• Dobsonian

• Fork

Answer explanation

The Equatorial mount is designed to align with the Earth's axis, allowing telescopes to track celestial objects as the sky rotates. This makes it ideal for long observations of stars and planets.

Which type of telescope is generally considered the best for astrophotography due to its compact design and versatility?

• Refractor

• Reflector

• Catadioptric

• Radio

Answer explanation

Catadioptric telescopes combine lenses and mirrors, making them compact and versatile. This design minimizes optical aberrations, making them ideal for astrophotography, unlike refractors and reflectors which can be bulkier.

What is the primary advantage of space telescopes like the Hubble Space Telescope over ground-based telescopes?

• They are cheaper to build and maintain.

• They are not affected by atmospheric distortion.

• They have larger apertures.

• They are easier to repair.

Answer explanation

The primary advantage of space telescopes like Hubble is that they are not affected by atmospheric distortion, allowing for clearer and more detailed observations of celestial objects compared to ground-based telescopes.

Which of the following telescopes is designed to study dark energy and dark matter?

• Hubble Space Telescope

• James Webb Space Telescope

• Euclid

• Very Large Telescope (VLT)

Answer explanation

The Euclid telescope is specifically designed to investigate dark energy and dark matter, aiming to understand the universe's expansion and the nature of its unseen components.

What is the main purpose of adaptive optics in large ground-based telescopes?

• To increase the aperture size

• To correct for atmospheric distortion

• To reduce the weight of the telescope

• To improve portability

Answer explanation

The main purpose of adaptive optics in large ground-based telescopes is to correct for atmospheric distortion, which blurs images caused by the Earth's atmosphere, allowing for clearer and more detailed observations of celestial objects.

Who was the first person to use a telescope to observe the moons of Jupiter?

• Isaac Newton

• Galileo Galilei

• Johannes Kepler

• Edwin Hubble

Answer explanation

Galileo Galilei was the first to use a telescope for astronomical observations, including the discovery of Jupiter's four largest moons in 1610, which provided crucial evidence for the heliocentric model.