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MrB398
2009-Mar-02, 01:17 PM
Sounds very intriguing.

http://www.foxnews.com/story/0,2933,501891,00.html

I am confused on something the article points out that maybe you astronomy buffs could clarify:

"The Earth's disk is a bit smaller than the sun's when viewed from the moon; on Earth, the moon just about covers the sun".

If the moon has 1/4 the diameter of the earth and just about covers the sun from the earths point of view, wouldn't a view from the moon show a much larger earth completely blocking the sun and then some?

Hornblower
2009-Mar-02, 01:28 PM
Sounds very intriguing.

http://www.foxnews.com/story/0,2933,501891,00.html

I am confused on something the article points out that maybe you astronomy buffs could clarify:

"The Earth's disk is a bit smaller than the sun's when viewed from the moon; on Earth, the moon just about covers the sun".

If the moon has 1/4 the diameter of the earth and just about covers the sun from the earths point of view, wouldn't a view from the moon show a much larger earth completely blocking the sun and then some?Yes indeed. The Earth's disk would have nearly 4 time the diameter of the Sun's disk. The writer was mistaken, and shame on the editors for not catching it.

NEOWatcher
2009-Mar-02, 01:29 PM
I am confused on something the article points out that maybe you astronomy buffs could clarify:

"The Earth's disk is a bit smaller than the sun's when viewed from the moon; on Earth, the moon just about covers the sun".
I'm confused, but on a different aspect of that statement.

Your statement sounds like you are not considering the size of the sun, and the projection of the tangents that creates the cone shaped umbra.

I was under the assumption that the moon is smaller than the size of Earth's umbra at the moon's distance. (about 2x +/- depending on orbit)

So; wouldn't the Earth seem the size (~2x) of the sun? Or is it that eccentric that umbra could be smaller than the moon's diameter. (and the statement is still wrong in that it sounds like an absolute)

Edit: Thanks Hornblower, we must have crossed posts in the mail.

hhEb09'1
2009-Mar-02, 02:18 PM
Yeah, they're about the same distance from the sun, they're the same distance apart (duh), and the earth is four times bigger than the moon.

What else did they screw up? :)

ETA: Ho! Fraser did a story on it (http://www.bautforum.com/universe-today-story-comments/84990-kaguya-captures-eclipse-moon.html#post1438494), as did the Bad Astronomer (http://blogs.discovermagazine.com/badastronomy/2009/02/19/what-does-a-lunar-eclipse-look-like-from-the-moon/). The reason that statement is in parentheses is it was apparently added by the editors--thinking that the bright ring around the earth were glimpses of the sun itself, rather than just the glow of the earth's atmosphere. Sheesh.

And here are some more images (http://www.jaxa.jp/press/2009/02/20090218_kaguya_e.html)from the original

I just now used their SEND NEWS TIPS link to inform them, "anonymity guaranteed" :)

Blue Fire
2009-Mar-02, 04:33 PM
Great catch, folks! It's stuff like this that needs to be questioned and corrected quickly as I'm guessing that most of the public just eats up the mistakes without a second thought. And then I envision some student doing a homework assignment on eclipses that ends up quoting a faulty Fox News report about the size of the Earth's disk.

grant hutchison
2009-Mar-02, 04:59 PM
And then I envision some student doing a homework assignment on eclipses that ends up quoting a faulty Fox News report about the size of the Earth's disk.Just so long as the teacher isn't daft enough to use Fox News as a primary resource, there would still be a useful learning experience in there for the student, eventually. :)

Grant Hutchison

2009-Mar-05, 05:10 PM
I wouldn't bet on that!

Yes, I agree the article was wrong. However, would some of the sunlight be refracted by the Earth's atmosphere to a sufficient extent to ensure that the Sun didn't disappear from view completely?

Alan

Just so long as the teacher isn't daft enough to use Fox News as a primary resource, there would still be a useful learning experience in there for the student, eventually. :)

Grant Hutchison

grant hutchison
2009-Mar-05, 07:00 PM
Yes, I agree the article was wrong. However, would some of the sunlight be refracted by the Earth's atmosphere to a sufficient extent to ensure that the Sun didn't disappear from view completely?The sun's light wouldn't disappear from view, certainly.
But when do we consider that the sun has set: when the solar disc is obscured by the curve of the Earth, or when its refracted red light fades from the sky? I think most people would choose the former.
In the case of the Earth eclipsing the sun, the solar disc is completely obscured by the Earth's disc. But an observer on the moon would see a ring of illuminated atmosphere still glowing red. That's every post-sunset and pre-sunrise red sky in the world, seen all at once. :)

Grant Hutchison