Standard Candle

What is the main method used to measure distances to objects beyond our own galaxy, as described in the passage?

• Analysing the redshift of distant galaxies

• Measuring the gravitational lensing effects of massive objects

• Comparing the observed brightness of an object to its known intrinsic brightness

• Detecting the motion of distant objects relative to each other

Answer explanation

Answer C: Comparing the observed brightness of an object to its known intrinsic brightness is correct. This method, using standard candles, measures distances to objects beyond our galaxy.

• Answer A: Redshift measures how much the light has shifted but doesn’t directly measure distances.

• Answer B: Gravitational lensing shows how light bends around massive objects but isn’t used to measure distances.

• Answer D: Motion relative to each other doesn’t measure distance directly.

What characteristic of light is used to measure enormous distances in space?

• Speed

• Wavelength

• Intensity

• Colour

Answer explanation

Answer C: intensity is correct. Astronomers measure distances by comparing the observed brightness of objects like Cepheid variables to their known luminosity.

• Answer A: Speed is not used for measuring distances.

• Answer B: Wavelength relates to color but isn't used for distance measurement.

• Answer D: Colour indicates motion, not distance.

What type of stars are used as "standard candles" to measure distances to more distant objects?

• Red giant stars

• Neutron stars

• Cepheid variable stars

• Type 1a supernovae

Answer explanation

• Answer C: Cepheid variable stars is correct. They are used as standard candles to measure distances.

• Answer A: Red giant stars are not typically used as standard candles.

• Answer B: Neutron stars are not used for measuring distances as standard candles.

• Answer D: Type 1a supernovae are also used as standard candles for distance measurement.

Why are type 1a supernovae useful as standard candles for measuring distances to distant galaxies?

• They have a consistent intrinsic brightness that can be calculated through the rate that they fade

• They can be observed even when individual stars in the galaxy are not visible

• Their brightness varies in a way that is directly related to their distance

• All of the above

Answer explanation

• All of the options are correct.

• Answer A: Consistent intrinsic brightness allows Type Ia supernovae to serve as reliable standard candles.

• Answer B: Visibility even in distant galaxies makes them useful for measuring distances where individual stars can't be observed.

• Answer C: Brightness variation tied to distance is another reason they are effective standard candles.

The method of using standard candles to measure distance has limitations. What is the furthest distance that can be measured using individual stars as standard candles?

• 1 light-second

• 4.24 light years

• 40,000,000 light years

• 2.5 million light years

Answer explanation

Answer D: 2.5 million light years is correct. This is the maximum distance where individual stars, such as Cepheid variables, can be used as standard candles to measure distances accurately.

Studying distant objects in the universe can provide insights into the history and origin of the universe. What is the key reason for this?

• The light we observe from distance objects is actually much older

• Distant objects are moving away from us at a faster rate

• Distant objects are much larger and brighter than nearby ones

• Distant objects are more likely to contain exotic matter and energy

Answer explanation

Answer A: The light from distant objects is older is correct, allows us to look back in time, providing insights into the early history and origin of the universe.

• Answer B: The faster rate of movement of distant objects doesn’t directly explain the universe’s history.

• Answer C: Distant objects are not necessarily larger or brighter.

• Answer D: Exotic matter and energy are not the main reason for understanding the universe’s history.