Earth, Solar System and Milkyway Galaxy

Comments and questions about the APOD on the main view screen.
ngungo
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Earth, Solar System and Milkyway Galaxy

Post by ngungo » Sat Jul 16, 2005 6:40 pm

I am not a student of astronomy, however I always have questions about the ralative position of these heaven objects:

1. Is the Earth's orbital plane (maybe the same as the solar plane) parallel with the Milky Way Galaxy plane?

2. What time of the year that, at night when we look into the sky above we would look into the center of Milky Way Galaxy?

Thanks,
ngungo

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BMAONE23
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Post by BMAONE23 » Tue Jul 19, 2005 5:26 pm

1) The ecliptic plane of our solar system lies almost on its side relative to the plane of the galaxy. Polaris lies in our arm of the spiral and slightly above the galactic ecliptic plane.

2) The (nearly) full moon was positioned over the galactic center during the solstice last month, so it is visible most of the late spring, summertime, and early autumn, at the right time of the evening.

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Post by Empeda » Wed Jul 20, 2005 4:09 pm

The Galactic Centre isn't visible (by visible light anyway) from the earth as it's obscurred by the dust in the spiral arms - I believe it's position is somewhere in Saggitarius.

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Post by Recycled Electrons » Thu Jul 21, 2005 12:18 am

To look in the direction of the galactic centre (or center, as we bastardized-English speaking Americans spell it) look at the constellation Sagittarius. The brightest stars of this constellation resemble a tea kettle, the spout of which is pointing to the galactic center.

ngungo
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Post by ngungo » Thu Jul 21, 2005 1:47 am

Thanks all for responses.

I figure that in order to "see" our Milky Way clearly, few conditions are needed:

. No light
. No moon
. Clear sky
. A time of the year that we can look into the galatic center (the earth' position is between the sun and galatic center).

I plan to go to a New Mexico desert where there is no light with a clear sky . I can choose a night without moon . But I don't know what time of the year and where on the sky to look at.

Can someone to sum it up for me. Thanks

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Post by makc » Thu Jul 21, 2005 7:19 am

according to horoscopes it should be (nov 22... dec 21) plus six month. in the sky it shoud be right somewhere on the south. Duh, don't listen to me, I have no idea.

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Post by BMAONE23 » Thu Jul 21, 2005 5:39 pm

If the galactic center lies in the constellation Sagittarius, then prime time for viewing would be when the constellation Sagittarius is opposite the sun. This optimum time would be 5-21 ~ 6-21 during Gemini as sagittarious is then opposite the sun.

Hope this helps

ngungo
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Post by ngungo » Thu Jul 21, 2005 7:48 pm

Both makc and BMAONE23 come up with the same answer:
nov22 ... dec21 + 6 months = may21 ... june21.

makc said right somewhere on the South.

OK! I got both and will make my schedule. But for my understanding why Sagittarius + 6 months = Gemini? I am oriental and I am not familiar with the Western Zodiac.

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Post by makc » Fri Jul 22, 2005 7:34 am

well, I got my answer from astrology. this "science" claims that position of constellations by the time you were born, affects your life. there are 12(?) constellations that sun is "crossing" on the sky along the year, and astrologists therefore assign constellation names to date ranges within the year, accordingly. for Sagittarius, it's (nov 22... dec 21). So, as BMAONE23 said,
prime time for viewing would be when the constellation Sagittarius is opposite the sun.
hence +6 month. or -6 :) and why south? because it's where sun is at daytime, so it's also where Sagittarius ought to be at night.

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Post by Empeda » Fri Jul 22, 2005 11:12 am

Not that you'll see anything of course, as the Galactic Centre isn't visible from the earth - you'd need your xray eyes....

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Post by ngungo » Fri Jul 22, 2005 2:14 pm

Empeda wrote:Not that you'll see anything of course, as the Galactic Centre isn't visible from the earth - you'd need your xray eyes....
Well! I would like to look at the Milky Way the way the ancient people saw it. Ancient people saw it all the times by naked eyes, in all civilizations, East and West. In the East they called it the Silver River. I figure since there was not electricity, there wasn't light at night; and it would be easier if no moon.

I also figure if I want to see the Milky Way, since our solar system is on the edge of the Milky Way, the position of the earth gots to be between the sun and the center of the galaxy to see the whole. This just happens at sometime of the year since the earth completes 1 orbit around the sun in a year.

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Post by Empeda » Fri Jul 22, 2005 2:19 pm

You can see the milky way at anytime of the year - it is the disc of our Galaxy - we are infact about two-thirds of the disc out not on the edge, though I see what you're thinking.... plus the orbit of the earth is nearer perpendicular to the galactic plane, so the Galactic Centre is always in the southern skies..

The disc however is full of dust, so greater distances are blocked, so it doesn't actually make an awful lot of difference what time of year it is - though I would presume there is a minor difference, it's probably insignificant.

If anyone from the southern hemisphere wants to correct that please feel free...
I'm an Astrophysics Graduate from Keele University, England - doesn't mean I know anything but I might be able to help!

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Post by ngungo » Fri Jul 22, 2005 4:15 pm

Great! Thanks Empeda,
ngungo

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Post by ngungo » Fri Jul 22, 2005 4:36 pm

BTW. Can anyone describe how the Milky Way looks at its best: naked eyes, no moon, no light and all ...

I would assume since we are inside the disc, the Milky Way would look as a band of concerntrated lumination stars running from one horizon to the other?

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Post by Empeda » Fri Jul 22, 2005 4:48 pm

Yep that's exactly what it looks like - make sure it's a dark night and you'll see it.

At first you might not see much, but as your eyes adjust you will see a haze from one horizon to the other appear almost directly above you - as your eyes adjust more and more it will become clearer.

Happy Gazing! :D
I'm an Astrophysics Graduate from Keele University, England - doesn't mean I know anything but I might be able to help!

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Post by BMAONE23 » Tue Jul 26, 2005 1:57 pm

Tthis link:
http://www.coasttocoastam.com/gen/page1 ... heme=light
shows a good representation of the solar ecliptic vs the galactic ecliptic.

Note the orbit of mercury vs the "galactic equator" noted on the left side of the image