# Excellent Exoplanet Illustration

1. Jun 21, 2012

### Ryan_m_b

Staff Emeritus
I'm amazed by this illustration

I've known that exoplanet discovery had come a long way in recent years but to see it like this is astonishing. I'm curious, what does the near future hold for this field?

2. Jun 21, 2012

### Bobbywhy

I agree it is an amazing illustration. Inside it there is some text and at the very bottom it says "THIS IS AN EXCITING TIME". Will someone please explain why the discovery of exoplanets makes this an exciting time? Weren't they generally expected to orbit most stars and recently our new technology in observing apparatus has enabled them to be found? Why would this cause excitement? Is there some implicit meaning that I am missing?

3. Jun 21, 2012

### phyzguy

Expecting to find them and actually finding them are two different things. When I go to a soccer game, I expect someone to score a goal, but it's still exciting when they actually do. Also, I think the variety of planet types is much more than anyone expected. No one predicted things like hot Jupiters and water-dominated planets than are actually being found. The possibility of confirming Earth-like conditions on some exoplanets in the near future, which is quite possible, also is exciting to most of us.

4. Jun 21, 2012

### Ryan_m_b

Staff Emeritus
Phyzguy covered expectation of discovery vs actual discovery quite well but just to put it another way: explorers who set out in history to find new lands did so with the expectation they would succeed but that probably didn't rival the feeling of succeeding! Personally I think that is why this is exciting, it is the realisation of the space exploration dream. Without near magic developments in technology observation of exoplanets from afar is as close as we are going to get to interstellar exploration. Couple that with the fact that all of these planets have been discovered within the last two decades (the first confirmed observation of an exoplanet was in 1995) and it seems like our exploration is only going from strength to strength. That's why I asked about near future projects, it will be facinating to see what the state of exoplanet exploration is like over the next few decades. How many will we have found? What will we be able to tell about them beyond their size, mass and distance from their sun?

5. Jun 21, 2012

### mheslep

Isn't this a little like saying with better space ships we could go there? My question is how much better must telescopes become to directly observe exoplanets?

That is, as II understand it exoplanets are essentially detected from the dip in their stars luminance during transit of the planet. To detect the reflected light from a planet, the challenge is not simply to detect the feeble light from the planet 20 or 50 ly away, but to do so in the presence of the direct light from its star. If astronomers are struggling to deal with the background glare of night time urban lighting, how will they manage a star?

6. Jun 21, 2012

### DaveC426913

Actually, only about 1/3 (279) of them are detected by transit. There are several other methods, including imaging (31).

The catalogue here shows this in detail.

7. Jun 21, 2012

### Bobbywhy

Oh, phyzguy and Ryan m b, thank you both for your comments and viewpoints on the subject of discovering exoplanets.
I am definitely impressed with the skills of those astronomers who can interpret these new data and infer so much. Interstellar exploration from here on earth is truly remarkable, and exciting, IMO.
The possibilities of "water-dominated planets" and "Earth-like conditions" seem to indicate a "We are not alone" wish as one source of the excitement. Does the idea that there may be life on some exoplanet add to the motivation for this exploration?

8. Jun 21, 2012

### DaveC426913

It's way exciting to me. I am encouraged to be alive during this time when we are on a new frontier, where our knowledge is growing exponentially.

9. Jun 22, 2012

### Ryan_m_b

Staff Emeritus
Good point though I think the potential improvements in telescope technology are vast compared to space "ships".
I found this cool proposed mission that wants to build a shade that blocks out the light of stars from telescopes during the hunt for exoplanets http://en.wikipedia.org/wiki/New_Worlds_Mission.

As with most proposed space missions it has a high chance of not happening but it illustrates what could be done if the funding was there.
Oddly enough it doesn't for me. Perhaps it's due to ignorance but I'm unaware of any possibility that exoplanet observation could go beyond determining very general attributes of a planet i.e. atmosphere make up, surface temperature etc. We might have some indication of life or at least the planet having the appropriate characteristics but even if it were teeming we wouldn't be able to tell anything about it.

10. Jun 22, 2012

Thanks for posting that!

I believe I'm going to print it out and put a copy on my wall and pass out others, perhaps even to strangers in the street.

It's amazing how many of them are hot Jupiters. So far, the only ones Ive heard of are Bellerophon (51 Pegasi b) and Dinky (Upsilon Andromedae Ab).

It'll get people thinking about science, and, by showing the excitement of true science, hopefully it will bite into the market for pseudo-science.

Last edited: Jun 22, 2012
11. Jun 22, 2012

### DaveC426913

Well, don't spend too much on the first printing - it will likely be obsolete by the time you find the sticky tack. They're discovering new planets at an ever-increasing rate.

12. Jun 22, 2012

### Staff: Mentor

I'm thinking of starting my own exoplanet search project. :tongue:

13. Jun 22, 2012

Well, then, get to the back of a VERY long lineup!!!! :rofl::rofl::rofl:

14. Jun 22, 2012

### mheslep

Thanks for the link. Some of the 'planets' listed are companion brown dwarfs per the ref literature. Some of the literature states that anything above 13 Mjupiter is actually a brown dwarf or better. Then, one of the smaller bodies on that list, KOI-55 b, has this note:

However, I looked up HR 7899 on the list which definitely qualifies as a direct image observation.

Yep, ok. That's impressive.

Last edited: Jun 22, 2012
15. Jun 22, 2012

### Staff: Mentor

I think it's important to note that the size of the planets and the star in the picture would actually be far smaller than even 1 pixel if not for diffraction. So while we are seeing the light reflected from the planets and emitted from the star, we get no detail or anything. Call it "direct imaging" if you like.

16. Jun 22, 2012

### mheslep

I'm not so sure. This kind of thing has much more of an appeal to me than sending more rock pushing missions to Mars.

Direct high resolution imaging of planets never seen before would be a return to the sense of discovering what's out 'there', the way it was at the time of the first Moon landing, and in multiple ways: i) is this really doable?, ii) what will we see? There's little question that, for instance, a manned mission to Mars is technically possible, given the will to spend ~$500B,$1000B, whatever it may be, on ~five elite humans.

17. Jun 22, 2012

### mheslep

Yes of course there's diffraction but are you sure about the resolution? The planet scales shown in the picture are roughly correct according to the measured data, which lists those planets as roughly 1/15 the diameter of the star. How many pixels do you credit to the star, and then how much growth is due to diffraction?

http://exoplanet.eu/star.php?st=HR+8799

Last edited: Jun 22, 2012
18. Jun 22, 2012

### Staff: Mentor

Direct imaging of planets, like we do with Jupiter, Saturn, etc currently, is out of the question at the moment. The size of the mirror you would need to be able to obtain the required magnification, light gathering, and resolution is...crazy huge. MUCH bigger than we could possibly launch into orbit. Ground telescopes would be limited horribly by atmospheric turbulence, and although we have adaptive optics, they don't approach the scale of this kind of telescope.

19. Jun 22, 2012

### mheslep

Well that was my thought as well until I saw what's been done so far with imaging on ground based telescopes. I also read that, for instance, the spectral lines of photosynthetic chemicals are very distinctive.

20. Jun 22, 2012

### mheslep

You missed the point of my first post, which was to question not whether this was possible now, but would it be possible even a century from now given the resolving power needed and the contrast problems. I originally thought no, given the 'shadow box' techniques in use for many of the detections. But some of imaging work done so far is impressive.

21. Jun 22, 2012

### Staff: Mentor

22. Jun 22, 2012

### Staff: Mentor

If that was your point then I'd say you need to clarify a little. Anyways, most of the "shadow box" techniques are designed to block the light from the star so that we can see the light reflected from the planets effectively without the star's light overwhelming the entire image.. This only requires enough resolving power to give good separation between the star and it's planets in the image, so it is far easier than trying to actually see the detail on any of the planets.

23. Jun 22, 2012

### mheslep

Clearly Sun sized stars at 140 ly can be resolved better than 1 pixel by Keck.

24. Jun 22, 2012

### Staff: Mentor

I just did the math, and while I'm not sure I was 100% accurate, when my numbers give me about [STRIKE]30 millionths[/STRIKE] 300 millionths of an arcsecond (0.0003)for the angular diameter of the star, I feel confident enough to run with it. If you disagree then please, do the math, as I would like to know if I did it correctly.

Last edited: Jun 22, 2012
25. Jun 23, 2012

### phyzguy

NASA has a proposed mission, called TPF (Terrestrial Planet Finder) to image exoplanets. There are two main concepts, TPF-I, based on an interferometer, and TPF-C, based on a coronagraph. Here is a web site:

http://exep.jpl.nasa.gov/TPF/tpf_index.cfm [Broken]

Last edited by a moderator: May 6, 2017