What would happen if the Moon was half the distance from Earth?

If the moon were half the distance away, Earth’s rotation would slow even more, dragging out our days and nights. If we were to survive the sudden earthquakes, volcanic eruptions, lengthening of days and nights, and higher tides, at least we’d get to see more frequent solar eclipses.

How does brightness change with distance?

Notice that as the distance increases, the light must spread out over a larger surface and the surface brightness decreases in accordance with a “one over r squared” relationship. The decrease goes as r squared because the area over which the light is spread is proportional to the distance squared.

Does luminosity depend on distance?

The difference between luminosity and apparent brightness depends on distance. To think of this another way, given two light sources with the same luminosity, the closer light source will appear brighter.

How would you relate the apparent brightness of light with the distance from the source?

The apparent brightness of a source of electromagnetic energy decreases with increasing distance from that source in proportion to the square of the distance—a relationship known as the inverse square law.

How is light intensity affected by distance?

There is an inverse relationship between distance and light intensity – as the distance increases, light intensity decreases. The light intensity is inversely proportional to the square of the distance – this is the inverse square law.

How does the brightness of light change when the source is held twice as far away?

How does the brightness of light change when a point soure of light is brought twice as far away? If its twice as far the light will be twice as bright. At what distance from earth is the gravitational force on an object zero? No matter how far away, the earth’s gravitational force approaches, but never reaches zero.

How would its luminosity change if the distance between Earth and the star were to double?

The total energy output per second of a star is called its luminosity, L, sometimes written as L*. If we double the distance from the star to 2r this same amount of energy is now distributed over four times the surface area, that is 4A.

What is the relationship between luminosity and distance?

At a particular Luminosity, the more distant an object is, the fainter its apparent brightness becomes as the square of the distance.

Why does light dim over distance?

Light gets dimmer with distance based on the inverse square law. This means that because an object does not give off, or reflect an infinite number of photons, the further away from the source an observer gets, the greater the ratio of space per photon.

What is the brightness of the Moon during its phases?

The brightness of the Moon changes dramatically as its phase changes. During first and third quarters, the visible Moon is 50\% illuminated by the Sun, but its brightness is only about 8\% of full Moon — an increase of 2.7 magnitudes.

What percentage of the Moon is illuminated by the Sun?

During first and third quarters, the visible Moon is 50\% illuminated by the Sun, but its brightness is only about 8\% of full Moon — an increase of 2.7 magnitudes. The Moon’s visual albedo on its illuminated segment gets progressively smaller as the angle between the Earth and Sun on the Moon (phase angle) increases.

How bright is the full moon at first quarter?

So if the full Moon as seen on Earth has a visual magnitude of –12.7, its brightness at first quarter (phase angle 90 degrees) would be magnitude –10.0, a brightness reduction of 12x. Since we see the Moon half illuminated by the Sun at first quarter, a 6x brightness reduction implies an effective lunar albedo reduction from .12 to .02.

What would happen if the Moon was zero degrees full?

On Earth, we never see a perfectly full Moon, since the true phase angle we see is in the order of 5 degrees. With a zero degree phase angle the Moon would be in Earth’s shadow, and we would experience a total lunar eclipse. Apollo astronauts reported that a true full Moon is about 30\%…