Gravitational Lensing

[StringJunky]

A question inspired by another thread on the same subject sprang to mind that has puzzled me for about 10 years.

 

Round about late December of 2000 there was an occultation of Venus by the Moon. The atmospheric conditions that evening were crisp and clear with Venus in sharp view which I knew from the news somewhere was due to pass behind the Moon through its exact centre. The Moon was in fine crescent phase (might have been a New Moon.). Venus passed behind the Moon into the lit side and passed out the the unlit side such that the Moon and Venus looked like the Islamic symbol.

 

The size and intensity of Venus was pretty good before it passed behind but as it came back in to view for about 30-60 minutes it was several times bigger and much more luminous compared to before the occultation...then it dimmed and reduced to its previous intensity and size.

 

It was an amazing spectacle and the geometry looked absolutely perfect with Venus looking unreally intense and large...I was quite moved by it.

 

Was this phenomenon caused by the Moon lensing the light of Venus?

Edited July 29, 2011 by StringJunky

[Jacques]

Hi

First the mass of the moon is to weak for a gravitationnal lensing that maybe observable.

The moon has pratically (almost 0) no atmosphere to produce an atmospheric lensing.

 

If it was the new moon it was probably close to your horizon. Earth atmosphere may plyed a role.

But I have a simple explaination. When Venus passed behind the moon it was not long after the sunset, so I guest that the sky was blue and Venus was appearing dimer because the contrast between venus and the sky was lower. Also it entered in lit section of the moon so also no big contrast between venus and the moon.

A rought calculation gave me an hour long occultation passing by the center of the moon.

During one hour the sky get pretty dark and your eye are adapted to dark and venus contrast against the sky was big also the contrast with the moon also was high because it came back on the dark side of the moon.

After sometime your eyes got used to it or may be venus got closer to the horizon and was dimmed by atmospheric absortion.

 

I experienced many time this "WOW look how venus is big" specialy when I spot venus early in the evening and I go check an hour later.

[StringJunky]

Hi

First the mass of the moon is to weak for a gravitationnal lensing that maybe observable.

The moon has pratically (almost 0) no atmosphere to produce an atmospheric lensing.

 

If it was the new moon it was probably close to your horizon. Earth atmosphere may plyed a role.

But I have a simple explaination. When Venus passed behind the moon it was not long after the sunset, so I guest that the sky was blue and Venus was appearing dimer because the contrast between venus and the sky was lower. Also it entered in lit section of the moon so also no big contrast between venus and the moon.

A rought calculation gave me an hour long occultation passing by the center of the moon.

During one hour the sky get pretty dark and your eye are adapted to dark and venus contrast against the sky was big also the contrast with the moon also was high because it came back on the dark side of the moon.

After sometime your eyes got used to it or may be venus got closer to the horizon and was dimmed by atmospheric absortion.

 

I experienced many time this "WOW look how venus is big" specialy when I spot venus early in the evening and I go check an hour later.

 

If the Moon has insufficient mass to cause that then that blows that idea out the window. It just seemed odd that it was so bright as it reappeared and seeing Lensing mentioned earlier I wondered. The Moon was at about between 1 and 2 0 clock in position so it was quite high up. I remember it was very clear sky and depth of vision into the night sky was exceptional with many stars seen. It occurred about 6ish which at that time of the year in the UK it's properly dark...sunset occurs about 4pm. It must have been the limits of human vision and some atmospheric effect in combination then.

 

Reading a wiki on proofs for Relativity it mentions the 1919 experiment by Eddington which showed it correctly predicted the deflection of a star's light. Maybe I'm using the wrong terminology and should perhaps call it deflection rather than lensing or are they the same?

Edited July 29, 2011 by StringJunky

[Jacques]

...the 1919 experiment by Eddington which showed it correctly predicted the deflection of a star's light by the sun

The mass of the sun is big enought so we can detect some deflection of star,s light during total eclipse. The deflection is very small but mesurable .