Orange Shade and Unusually bigger moon!

[rizzi]

Hello. You might probably think that I'm stupid coz I asked this question. Well, I am very new to astronomy and I currently have a 50mm Ross London brass telescope.

Today evening I noticed that the moon was half visible and it was just above the horizon with an orange shade on it (usually this time the moon is somewhere between overhead and the horizon) and it was quite near. When I had the telescope pointed I took a few pictures but the pictures came out the usual lunar white!

Within a few hours the moon started going upwards fast, losing the orange colour and was becoming more and more smaller in size ( for comparision it went from O to o , it a bit smaller than usual today).

I was hoping for a possible explanation as such knowledge would only make me better at stargazing.

I am from Bangladesh

Thank you

[rowan46]

http://home.hiwaay.net/~krcool/Astro/moon/moonorange/

http://science.howstuffworks.com/question491.htm

[LukeSkywatcher]

http://home.hiwaay.n...oon/moonorange/

http://science.howst...question491.htm

Both good links. Pretty much explains the "Moon Illusion".

[Astroegg]

Hi rizzi,

You have several questions so I'll do my best...

The Moon is brightly lit because sunlight is reflected off the surface of the Moon (The Moon has no light source of its own, it is only the light from the Sun bouncing off the lunar surface back towards Earth). The Orange colour of the Moon is because the light is travelling through the Earth's atmosphere and being refracted (rather like a ray of light is "bent" when passing through water or glass into the colours of the rainbow.)

Since the Moon is low on the horizon when you first see it rise, the light reflected towards you off the surface of the Moon has to pass through more of the Earth's atmosphere because it is at a shallow angle, so the light will be refracted more (towards the red colours), hence its slightly orange colour. As the Moon climbs higher in the sky, the angle the rays of reflected light coming from the Moon gets more direct, so we see them through less of the atmosphere, and consequently the refraction becomes less and they appear in their more natural 'lunar white' state.

When you tried to photograph the orange Moon, your camera may have been on an auto exposure setting, which will try and compensate for the dark image you are trying to take, so will hold open the shutter for slightly longer than in normal daylight therefore capturing more light. This will slightly 'over-expose' the Moon and wash out the orange colour you see with the naked eye. Try manually setting the expose time to shorter exposures and you will get more true colour results - practice makes perfect to find the optimum settings your camera requires.

The difference in comparative size you noticed as the Moon rose higher in the night sky is actually a phenomenon which makes it look like the Moon is bigger when it is near the horizon, whereas in actual fact the Moon is the same apparent size when it is high up in the sky as it is near the horizon. It is not entirely known why this optical illusion occurs but the are many explanations you can find on the Internet which document the peculiarity.

Hope this helps you in your quest for better stargazing.

Regards,

Astroegg.

[Matt Scunthorpe]

Had a read of the links above, helped me understand the increased atmosphere near the horizon rather than overhead too.

Another note on the apparent size of the moon. When it is near the horizon, and you have other reference objects such as trees, buildings etc. Your mind knows the Moon is much bigger, so the Moon appears larger. When it in overhead, there are no other reference objects, so the moon seems smaller, or its natural size.

[Welrod50]

It was exactly the same here in the Midlands (UK) just. Large and orange, and now obscured by cloud, so I've come in to browse here.

Scott

[Astroegg]

In this APOD, a photographer has taken several photos of the Moon as it rises above the horizon. You will see the sequence shows the Moon to be the same size as it rises whilst also nicely showing the orange colour near the horizon, but paler colour higher above the horizon. The final frame of the photo was taken with a longer exposure, which makes the last moon a much brighter white (overexposed) compared to the others, thus showing all the points you questioned in your post.

[umadog]

Here's a paper on the moon illusion. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC26692/

It's certainly related to distance cues. You can test this yourself. Draw a filled black circle on a piece of paper and stare at it for a minute until you get an after-image. Then "project" this after-image onto different objects (blink if you need to refresh it). It will appear bigger when you project on more distant objects.

[rizzi]

Wow thank you so much guys! really helped me out alot!