# Mass of the Moon and Gravitational Lensing

• I
• Helena Wells
In summary, the effect of lensing would be to make the moon's apparent angular size smaller all the time, not just during eclipses. This would occur even if there was a negligible amount of lensing.
Helena Wells
During an eclipse the Moon covers the Sun.However this shouldn't be happening due to gravitational lensing we should be able to see some light?

Is the mass of the Moon not big enough or photons do reach us but they are so little our eyes can't detect them?

A. Lensing is negligible.
B. The effect of lensing would be to make the moon's apparent angular diameter smaller all the time, not just during eclipses.
C. You would have total and annular eclipses. Just like we do now.

Motore, Ibix and berkeman
I just told you the formula for the angular deflection of light in the Elon Musk thread! Plug the numbers in and see how much angular deflection you get.

etotheipi, berkeman, Vanadium 50 and 2 others
And after plugging in the numbers for the lensing then compare that to the difference in angular size depending on orbital distance to the moon.

A high definition computer would be able to understand the difference?

What is a " high definition computer"? And what "difference"? The effect of lensing would be to make the moon's apparent angular diameter smaller all the time, not just during eclipses.

Helena Wells said:
A high definition computer would be able to understand the difference?
Never anthropomorphize high definition computers. They hate it when you do that.

The effect of lensing would be to make the moon's apparent angular diameter smaller all the time, not just during eclipses.
I think the point he's hoping to make is that it is only during an eclipse that the small amount would make an obvious difference - because of the sun.

But no. Even if it were a non-negligible amount of lensing, the Moon's elliptical orbit means its apparent size changes noticeably from eclipse to eclipse anyway. So you'd get Vanadium's total and annular eclipses anyway.

Helena Wells said:
A high definition computer would be able to understand the difference?
Why would a computer have anything to do with the angular resolution of a telescope? Unless you've got one of those magic CSI computers that can zoom-and-enhance and read a license plate from a single pixel reflection in somebody's eyeball?

Helena Wells said:
Is the mass of the Moon not big enough or photons do reach us but they are so little our eyes can't detect them?

Neither. During a total solar eclipse the angular size of the Moon is enough larger than the angular size of the Sun that the miniscule gravitational lensing effect of the Moon is not enough to bend any of the Sun's light sufficiently for us to see it.

Back to the question at hand for a second. I need a little help. I know these are small effects
B. The effect of lensing would be to make the moon's apparent angular diameter smaller all the time, not just during eclipses.

It is hard for me to understand that the lensing effect would be the same (or similar) for light from behind being occluded and light being emitted (or reflected).
So the sun (assuming it has a sharp limb) actually looks smaller than its size because of gravity acting on light?

B. The effect of lensing would be to make the moon's apparent angular diameter smaller all the time, not just during eclipses.

I don't think this is correct. Gravitational lensing refers to an object bending light coming from objects behind it. The Moon's apparent angular diameter normally is determined by light reflected from the Sun off the Moon (or from the Earth off the Moon, if you are seeing "the old moon in the new moon's arms"), not by light coming from behind the Moon. Only during an eclipse is there a light source right behind the Moon such that lensing by the Moon could affect the Moon's apparent angular diameter.

The effect of lensing would be to make the moon's apparent angular diameter smaller

Also, the effect of lensing by object A of light coming from object B, behind object A, is not to make object A's apparent angular diameter smaller; it's to make object B's apparent angular diameter larger.

hutchphd
Maybe I should have said "effective angular diameter". If lensing moves the direction of light from an object behind the moon so that it is no longer obstructed, that means the moon obscures less of it, i.e. the effective angular diameter is less.

If lensing moves the direction of light from an object behind the moon so that it is no longer obstructed, that means the moon obscures less of it, i.e. the effective angular diameter is less.

I see what you mean; I think a simpler and more intuitive way to describe it is that it makes the apparent angular diameter of the object behind the moon larger.

etotheipi, phinds, Ibix and 2 others

## 1. What is the mass of the Moon?

The mass of the Moon is approximately 7.34 x 10^22 kilograms.

## 2. How is the mass of the Moon measured?

The mass of the Moon is measured using Newton's law of universal gravitation, which takes into account the Moon's orbital period and distance from the Earth.

## 3. How does the mass of the Moon affect Earth's tides?

The mass of the Moon plays a significant role in creating Earth's tides. The gravitational pull of the Moon on the Earth's oceans causes them to bulge, creating high tides.

## 4. What is gravitational lensing?

Gravitational lensing is a phenomenon in which the gravity of a massive object, such as a galaxy or a cluster of galaxies, bends and distorts the light from objects behind it. This can create multiple images of the same object or even magnify the image.

## 5. How does the mass of the Moon contribute to gravitational lensing?

The mass of the Moon is not significant enough to contribute to gravitational lensing on its own. However, it does play a role in the overall gravitational field of the solar system, which can affect the bending of light by more massive objects such as galaxies.

Replies
8
Views
780
Replies
58
Views
4K
Replies
4
Views
1K
Replies
125
Views
4K
Replies
1
Views
707
Replies
11
Views
708
Replies
5
Views
1K
Replies
8
Views
3K
Replies
7
Views
2K
Replies
2
Views
799