Astronomy: Understanding Constellations

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What is the definition of 1 parsec in terms of parallax angle?

The distance to a star that has a parallax angle of 0.1 arc-seconds

The distance to a star that has a parallax angle of one arc-second (correct)

The distance to a star that has a parallax angle of 10 arc-seconds

The distance to a star that has a parallax angle of 0.01 arc-seconds

What is the approximate diameter of the observable universe?

9 × 10^10 ly (correct)

9 × 10^12 ly

9 × 10^11 ly

9 × 10^9 ly

How many stars are there approximately in a big galaxy?

10^12 (correct)

10^10

10^11

10^13

What is the conversion factor from AU to ly?

1 AU = 1.5 ly Signup and view all the answers

What is the unit of distance used to measure distances to the most distant galaxies?

Gpc Signup and view all the answers

Why is the speed of light a limiting factor in observing the universe?

Because light takes a long time to travel long distances Signup and view all the answers

What happens to radiation as it passes through the Earth's atmosphere?

It may be absorbed, refracted, or scattered Signup and view all the answers

Why do we see blue skies and red sunsets?

Because of the atmosphere's effect on light wavelengths Signup and view all the answers

Why do astronomers prefer to site optical telescopes on the tops of mountains?

To reduce the adverse effects of the atmosphere on images Signup and view all the answers

What is the approximate height of the Earth's atmosphere?

100 km Signup and view all the answers

What has been the advantage of using telescopes on orbiting satellites?

They have greatly increased the resolution of images from space Signup and view all the answers

What is the name of the famous telescope that was launched in 1990?

The Hubble telescope Signup and view all the answers

What is the main focus of the search for extraterrestrial intelligence?

Studying planetary systems like our own solar system Signup and view all the answers

How many planetary systems had been identified by the start of 2014?

More than one thousand Signup and view all the answers

What is the purpose of identifying patterns of stars in the night sky?

To distinguish different parts of the night sky Signup and view all the answers

What is unique about Kepler 186f?

It is the most Earth-like planet Signup and view all the answers

What do the stars within a constellation have in common?

Nothing, they are arbitrary patterns Signup and view all the answers

What is the primary reason why objects in our solar system are visible?

They reflect the Sun's radiation Signup and view all the answers

What is a planetary system?

A collection of non-stellar masses orbiting a star Signup and view all the answers

What is the approximate age of the Sun and the Earth?

4.5 billion years Signup and view all the answers

What is the main difference between a planet and a star?

The mass of the celestial body, which determines if nuclear fusion occurs Signup and view all the answers

What is the term for objects orbiting around planets?

Moons Signup and view all the answers

What is the additional criterion used to distinguish planets from smaller orbiting masses?

The planet has cleared its neighbourhood of smaller masses close to its orbit Signup and view all the answers

What is the process believed to have formed planetary systems?

The same process as the formation of stars Signup and view all the answers

What is the wavelength of the light emitted?

6.6 × 10 –7 m Signup and view all the answers

What is a paradigm in scientific terms?

A pattern of beliefs and practices that define a particular branch of science Signup and view all the answers

Who popularized the phrase 'paradigm shift'?

Thomas Kuhn Signup and view all the answers

What is an example of a paradigm in this chapter?

The Earth is at the centre of the universe Signup and view all the answers

When was the phrase 'paradigm shift' first popularized?

The early 1960s Signup and view all the answers

What is the phrase 'paradigm shift' used to describe?

Changes in scientific beliefs and practices Signup and view all the answers