Exploring the Sky 2 Flashcards

Lectures 4-8

1
Q

If a star is fainter, it’s magnitude will be…

A

Higher

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2
Q

What is Betelguese’s magnitude?

A

0.45

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3
Q

What is Rigel’s magnitude?

A

0.18

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4
Q

What is Polaris’s magnitude?

A

1.97

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5
Q

If the magnitude difference is 1, what is the brightness?

A

2.5

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6
Q

If the magnitude difference is 2, what is the brightness?

A

6.3

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7
Q

If the magnitude difference is 3, what is the brightness?

A

16

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8
Q

If the magnitude difference is 4, what is the brightness?

A

40

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9
Q

If the magnitude difference is 5, what is the brightness?

A

100

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10
Q

What magnitude can the naked eye see?

A

6 magnitude and higher

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11
Q

The area of a lens is proportional to the square of what?

A

It’s diameter

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12
Q

Why do some stars have variable magnitude?

A

Because they pulsate

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13
Q

In some cases, the period of pulsation is related to what of a star? (2 factors)

A

Size and Luminosity

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14
Q

What have Cepheid vairables become important for?

A

Establishing the distance of external galaxies

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15
Q

How are Cepheid variables used to establish the distance of external galaxies?

A

Their apparent magnitude is measured the matched with the intrinsic brightness of Cepheid variables in the milky-way

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16
Q

Solar time is defined as what?

A

The hour angle of the sun plus 12 hours

17
Q

What does the hour angle of the sun depend on? (2 factors)

A
  • The rotation of the earth

- The sun’s revolution around the ecliptic