Distances

The video explores the history of measuring astronomical distances, starting with ancient Greek methods to calculate Earth's size and extending to modern techniques for determining distances to stars. It highlights the importance of the astronomical unit and parallax in understanding the solar system and beyond. The video also discusses how brightness and spectroscopy help determine star properties, emphasizing the role of curiosity in scientific discovery.

What did ancient people believe about the stars?

• They were holes in a crystal sphere.

• They were distant planets.

• They were reflections of the sun.

• They were gods watching over Earth.

How did Eratosthenes calculate the Earth's circumference?

• By measuring the shadow of a mountain.

• By using the angle of the sun's rays in two cities.

• By observing the stars' positions.

• By calculating the distance to the moon.

Who used the Earth's size to calculate the distances to the Moon and Sun?

• Ptolemy

• Aristarchus of Samos

• Eratosthenes

• Hipparchus

What is the astronomical unit (AU) primarily used for?

• Measuring the distance between stars.

• Calculating the size of the Earth.

• Determining the distance from Earth to the Sun.

• Measuring the brightness of stars.

How was the astronomical unit accurately measured in the 1960s?

• Using radar pulses bounced off Venus.

• By observing solar eclipses.

• Using the transit of Mercury.

• By measuring the distance to Mars.

What is the main limitation of using parallax to measure star distances?

• It only works for stars within 100 light years.

• It needs a large baseline, like Earth's orbit.

• It requires a telescope.

• It is only accurate for very bright stars.

What unit is based on the distance light travels in a year?

• Kilometer

• Parsec

• Astronomical unit

• Light year

How can the brightness of a star help determine its distance?

• By observing its position in the sky.

• By comparing it to a star with known distance.

• By comparing it to the brightness of the Sun.

• By measuring its color.

What role does spectroscopy play in measuring star distances?

• It measures the star's temperature.

• It determines the star's mass.

• It helps identify the star's chemical composition.

• It ensures stars are of the same type for brightness comparison.

What was the starting point for measuring astronomical distances?

• The curiosity of ancient Greeks about Earth's size.

• The invention of the telescope.

• The discovery of the light year.

• The development of space-based satellites.