Star-hopping a way home for a superman; astronomers needed

[chasrob]

You're right, I've been observing the sky with my 8" Dobsonian on-and-off for 30 years and I can't tell the difference in color of an 0,B,A,F, or G class star. The only color I can discern in star-points is a faint orange tinge with M class or K's like Aldebaran. Which is why I chose stars like Betelgeuse and 6 Gem for the MC's star hopping.

Hmm. Has anyone calculated the H magnitude of earth?

 

[snorkack]

Also, once he finds Sol, how does he find Earth? Stars don't twinkle in space. I think this is where a knowledge of astronomy is more important.

That should be easy!

The starry sky is exactly the same for hundreds of AU from Sun. So all light dots that do not belong are planets (or nearby asteroids or comets).

Stay out of the ecliptic, and Sun cannot obscure any planets, nor can planets be in conjunction. Within the few AU of Sun, the light spots of negative magnitude are Jupiter, Venus, Earth, Mercury and Mars if nearby.

And Earth is the only one with a bright, conspicuous satellite.

I'm thinking you could match all the angles of that photo but still be thousands of lys away from the sun's position.

Half a degree is the width of Moon disc - with quite some detail for normal naked eye vision. It also is 9 mm at distance of 1 m.

If the Superman can measure the distance between 47 Tucanae and Small Cloud with half degree precision, then since the distance to 47 Tucanae is 14 000 ly away, you can only be 125 ly away from the line through Sun.

You can be a bit further along this line, but this would mean being off the Milky Way plane. The asymmetry of Milky Way and its rifts would give away this... so matching the intersection of the plane and the line gives the solar neighbourhood with error of maybe 200 ly.

The next pointers? I suggest Orion and Taurean Pleiades. Any others?

 

[chasrob]

[...]
Half a degree is the width of Moon disc - with quite some detail for normal naked eye vision. It also is 9 mm at distance of 1 m.

If the Superman can measure the distance between 47 Tucanae and Small Cloud with half degree precision, then since the distance to 47 Tucanae is 14 000 ly away, you can only be 125 ly away from the line through Sun.

You can be a bit further along this line, but this would mean being off the Milky Way plane. The asymmetry of Milky Way and its rifts would give away this... so matching the intersection of the plane and the line gives the solar neighbourhood with error of maybe 200 ly.

Right, he could get that angle down by that method. Wouldn't it help if also he estimated the http://upload.wikimedia.org/wikipedia/commons/f/f3/Magellanic_Clouds_%E2%80%95_Irregular_Dwarf_Galaxies_.jpg of 47 Tucanae and a line extended through the large and small clouds? Say, "47 Tucanae must be at a 10 o'clock position when the clouds are oriented horizontally"?

 

[snorkack]

Yes. He should estimate the angle, because this gives him his location along second direction.

I wasn´t sure what the baseline should be to measure the angle of Small Cloud-47 Tucanae from. My idea had been a line parallel to Milky Way. The line between Big Cloud and Small Cloud is another option, and a third obvious possibility is to use the elongation axis of Small Cloud.

Or maybe use all third, to check his naked eye impression for errors. After all, both Clouds are somewhat extended smudges.

 

[chasrob]

So, nobody's too impressed with my OP scenario using stars? Y'all have some great ideas, but the protag is... well, before he manifested he was a starving actor. Limited, IOW, with regard to most things involving geometry and trig. Plus according to the "laws" of the story he emerged from FTL naked, with no tools--sextants or whatever--to help him, except the Mark I eyeball.

BTW, some errors I made--

I'm writing a novel which has as a protagonist a super-powered being, like in the comics (only he is the sole such critter in the universe).
[...]
6 Geminorum is an M1Ia red supergiant with a galactic latitude of 188 deg., which means it's anti-center of earth.

I meant longitude of course. The Milky Way has a lot of arms, partial arms, and spurs, but it would be simple, I would think, to extend a straight line from that supergiant cluster to the center of the galaxy, then look for a certain spur 2/3 of the way out from the center.

From Betelgeuse, no bright red stars that would help, but white Bellatrix is mag 1.1 and the Orion Nebula is nearby so it's next.

Double checking, Bellatrix is ~190 ly from Betelgeuse and ~250 from Earth while the nebula is 1500 from the earth, so it should be behind Betelguese if you're there looking at Bellatrix, correct?

If so, what does the protagonist do from there?

 

[snorkack]

So, nobody's too impressed with my OP scenario using stars? Y'all have some great ideas, but the protag is... well, before he manifested he was a starving actor. Limited, IOW, with regard to most things involving geometry and trig.

My reasoning is that stars are lots of indistinguishable white dots. For naked eye and full sphere sky, about 5000 of them.

Nebulae are rather fewer and somewhat more distinctive:
galaxies - 3 or 4 (Magellanic Clouds, Andromeda, with good vision Triangulum)
globular clusters - 2 or 3 (Omega Centauri, 47 Tucanae, with good vision Hercules)
diffuse nebulae - I think 2 or 3 (Carina, Orion, maybe Lagoon)
supernova remnants - 0
planetary nebulae - 0
unresolved open clusters - not quite sure but guessing 10...20

Still, over 100 times fewer than stars. And unlike stars which are pure dots, nebulae have a bit more distinctive traits, like surface luminosity, shape... Easier to do memorizing and elimination.

If so, what does the protagonist do from there?

Orion?
I suggest two things:
try to identify and use the triangle of Orion´s Belt (Alnilam is luckily far behind the other two)
look for Taurean Pleiades.

 

[chasrob]

News http://www.redorbit.com/news/space/1112863504/earth-solar-system-on-spiral-arm-060313/ Relevant to my story. The sun is not on a spur, but perhaps a major arm of the galaxy, extending over to the Perseus Arm, not the Sagittarius. Using the star-hopping method, it should be easier to locate our star's neighborhood.