Science Buddies: "Ask an Expert"

Hi Guys!
I'd really like feedbac on the following ;
I would like to preform a project on finding planets, I have the equipment necessary, I just need a bit of luck
So, what i would do is make a chain of observations in one area of sky. I would image the sky at the same time and quardinates each nite.. I would be looking for a slight "wabble" in the stars... Just by about 0.000001 of a degree.. stacking the images would help find these differences.
And again, please give me your feedback!
Cheers!

Shamus

Wobble detection methods are ususally better suited for finding moons of visible planets than for detecting invisible planets. Do some research/reading on ideas that NASA is toying with to find planets in distant solar systems for some other approaches.

Hi There!
I did followup on some research last night, and the 2 primary ways of detecting invisible planets is the wobble of the mother star, or a slight dimming of the mother star when the planet passes infront..
The Transit method (Slight dips in the brightness) is what Nasa records with there space telescopes.
The Doppler method (Slight wobbles) is commonly used by amateur astronomers, looking for planets.
Cheers!

Shamus

There's a really interesting blog article here on the ScienceBuddies site you should check out:

https://www.sciencebuddies.org/blog/201 ... overed.php

At the bottom of the article appear a couple other links that describe some very interesting astronomy experiments you might want to consider.

Good luck with your work and HAVE FUN! : )

Thank you all for the help!
I've narrowed it down to a testable question; Which stars are exoplanets most common to find orbiting around?
I will look at a multitude of stars. (I.e Blue Supergiants, Red Supergiants, Red Hypergiants, Main sequence, white dwarfs, etc..)
Im going to be getting a DSLR (Canon), which will help greatly!
Im going to photography certain areas, leaving the shutter open for about 20-40 seconds.. at 50 seconds, the stars start to blur becouse of the movement.

Cheers!

Shamus

Beware: DSLR cameras probably aren't appropriate for this.

Digital cameras have RGB pixels in a geometric pattern to sample the image. The raw resulting image is the an assumption that the entire pixel is at the same intensity. Read up on Nyquist sampling theory. When applied in two dimensions, 2*sqrt(2) instead of the one dimensional factor of 2 comes into play. Unless you are planning on photographing through a telescope with considerable magnification, you won't have nearly enough resolution. Unfortunately, these resolution issues aren't your only problem.

Digital cameras do not have sufficient intensity ranges. If a star is in the image area (or just outside it), if your exposure is longer than the time it takes to saturate a pixel, a "bloom" effect will occur and affect surrounding pixels. If your exposure is short enough to avoid bloom, reflected light from the planet may not register above the noise floor.

Digital cameras also have a noise issue that shows up at low light levels. To reduce these artifacts, the newer digital cameras do some averaging of low level pixels which may hide the data you are looking for.

I'm no expert at all in methods for finding exoplanets. One remark, however, in science1997's followup posting triggers a concern.
The "wobble method" is also associated with the name Doppler. That name implies that it is not the sideways wobble that is being detected, but rather the radial wobble as expressed in a very small shift of the star's spectrum. A pretty fancy spectrometer would be needed to see that.
Be sure to read a bit more about the Doppler method before heading down a blind alley. Start at http://en.wikipedia.org/wiki/Doppler_spectroscopy.

Hi there!
Sorry about the delay..
I have started some testing, and it does work!
To test if my camera was sensitive enough, I tried to detect known planets. And surely enough the stars with planets showed a tiny movement (magnification was needed).

A thought on verifying your detection method. Have you applied your technique to a star that is known to NOT have a planet? The reason behind this is to rule out the rotation of the Earth itself and its movement around the Sun as any source of detected movement. Remember that the Earth rotates ~15 deg/hr toward the east. This equates to a velocity of about 1036 mi/hr eastward for an observer on the surface of the Earth at the equator. Unless you have a high quality tracking mount/tripod, this motion could be detectable and induce error.

Please post how things are going with your test rig.