by Czerno o » Sun Jun 05, 2016 9:47 am
@Ann : «And they say that the only human-made structure that can be seen from space is the Great Wall of China. »
Excuse me, I fail to understand the meaning, or at least, relevance, of your quote, Ann. You do not think the APOD photograph of the day was taken from Earth, do you ? Nothing could be more wrong !
Quoting its own caption, the APOD was captured in 2009 « from the Lunar Reconnaissance Orbiter»
There's of course no hope to catch see such a small object from a telescope on the Earth (angular dimension of the order of 4 ? meter/ ditance 400,000,000 meter ~ viz 10^-8 rad ~ viz 2 thousandths of arc seconds !). Incidentally, you probably couldn't discern the Great Wall from the Moon, either. Although it is a long structure, it's not wide enough.
@Ann : «And they say that the only human-made structure that can be seen from space is the Great Wall of China. »
Excuse me, I fail to understand the meaning, or at least, relevance, of your quote, Ann. You do not think the APOD photograph of the day was taken from Earth, do you ? Nothing could be more wrong !
Quoting its own caption, the APOD was captured in 2009 « from the Lunar Reconnaissance Orbiter»
There's of course no hope to catch see such a small object from a telescope on the Earth (angular dimension of the order of 4 ? meter/ ditance 400,000,000 meter ~ viz 10^-8 rad ~ viz 2 thousandths of arc seconds !). Incidentally, you probably couldn't discern the Great Wall from the Moon, either. Although it is a long structure, it's not wide enough.