Most of the systems they use in the show are real stars. I noted that a lot of the ones in the OP’s pics were used in various TOS and TNG episodes: Arcturus, Rigel, Antares, and Aldebaran, just off the top of my head.
I tried Googling for numbers with essentially no luck, so the following is based on fallible memory.
While bright giant stars like Antares, Betelgeuse, Rigel, etc., are very obvious in the sky, due to their intrinsic enormous output, they are relatively scarce among stellar populations. Somewhere around 90% of all stars are on the Main Sequence.
And of these, about 80% (or 72% of all stars) are class “M” red dwarfs – very small, very dim. Proxima Centauri and Barnard’s Star, the closest star and the 2nd closest after the Alpha Centauri triplet, are both class “M” and neither are visible without telescopes, despite being our next-door neighbors.
The Sun is “lower middle-class” by main sequence standards, being a “G2” type about 40% of the way up the main sequence. It’s very much “average” as stars go.
The giant stars, and even more so the supergiants, are that way because their outer layers are enormously distended by the intense heat of their cores. Some of them have radii reaching out to what would be the orbits of some of the planets in our system.
Oh, be a fine girl, kiss me.
O B A F G K M
http://hyperphysics.phy-astr.gsu.edu/hbase/starlog/staspe.html
Also, as has been stated, we go from rare with the O to very common with the M. Imagine a pyramid, with O being the apex, and M being the base, and one has a general idea of the population density of the various spectral types. (From memory of many, many different books, trying to find a cite site to link to…)
You actually don’t need any sunscreen. You just need to be very far away.
Story of our lives, I tell you! Just try to get into some of the hoity-toity condo neighbourhoods near the Galactic Core, and they don’t even look at us! Just because we live in the unfashionable end of the Eastern Spiral Arm of the Galaxy, they think they can lord it over us! Well, let me tell you…
Seriously, those pictures are amazing. 
:: Sunspace realises that Monty Python song is stuck in his head; he proceeds to blast it out with Sakutai Atsushi ::
well, since Star Trek has already been mentioned in this thread, how about fighting fire with fire?
*Star…Trekking
Across the Universe
Boldly going forward
'Cause we can’t find reverse!*
Curse you!
:: cranks up the SSQ ::
The New York Daily News Globe and Fun Facts about the Universe
All measurements given in miles. Adds up.
Maybe this will be beter…
C’mon
C’mon
C’mon
Let’s go space truckin’
Despite the fact that there are a lot of interesting articles on his website, I firmly believe that Jeff Rense is completely insane. He:
[ul]Believes that AIDS was created in a laboratory by government scientists.[/ul]
[ul]Claims that the 9/11 attacks were orchestrated by the CIA and possibly the Israelis.[/ul]
[ul]Believes the Illuminati and Zionists are in control of the world.[/ul]
[ul]Believes in UFOs and dedicates a substantial portion of his site and his show to talking about them[/ul]
[ul]Has guests who include “UFO expert” Peter Davenport and Israeli conspiracy theorist Barry Chamish who believes that the Mossad killed JFK and is a firm believer in Illuminati/Zionist domination despite being Jewish[/ul]
As if this were not enough, just look at him.
I have read a lot of his site and I really am convinced that he’s nuts.
Oh my Og…he’s Yanni’s grandfather!
I wish he’d included some moons in the sequence. How does the Earth’s moon compare with Mars/Mercury/Pluto? Are any of the other moons large enough to be worth showing against the planets?
But, really neat page!
Whoa, check out Uranus!
(Yes, I am 12 years old, why do you ask?)
Great site. That’s one to add to the bookmarks list. If I had to guess before looking at that, I would’ve thought red giants were 10 times the size of the sun, and the biggest in the universe got to maybe 20-50 times the diameter, but it looks like it’s even more than that.
What boggles my mind is thinking about the pressure that must be going on in the interiors. I mean, in just the Earth, the pressure at the core is thousands(?) of atmospheres, and it’s enough to heat the inside to the melting point. Now, imagine if you dug a hole in the surface of the sun that was the same distance as the radius of the earth…it would barely scratch the surface. And that’s with about 100 times(?) the gravitational force of the earth. With a star like Betelgeuse or Antares, by the time you got even 1/10th the way to the core you’d have pressures so great I can barely wrap my mind around it.
Ganymede, Jupiter’s biggest, is bigger but lighter than Mercury. So is Titan, Saturn’s biggest. They, Callisto, Io, our Moon, Europa and Triton all come in ahead of Pluto. But Mars is a lot bigger than even Ganymede.
I should have known you’d find a way to get Mars bragging rights! 
I was surprised to see that Mars is that small; I always thought it was around the same size as Earth and Venus.
But one day the Sun WILL be a red giant, as it dies out, just like Betelgeuse. It’ll eat some of the inner planets, it’ll get so big.
Now that questions about the author of that site have arisen, I did some checking around and calkalatin’:
Diameter of Earth: 12,756,300 m
Diameter of Sun: 1,400,000,000 m = 109 Earth diameters
1 Astronomical Unit (AU, Distance from Earth to Sun): 149,598,000,000 m = 106 Solar diameters = 11,727 Earth Diameters
Diameter of Antares: 3.8 AU = 406 Solar diameters = 44,564 Earth Diameters = 568,472,400,000 m