Wavelength will get shorter, and hence BLUESHIFTED Light source moving towards the observer, the observed.Observed wavelength will get longer, and hence Light source moving away from the observer, the.The Doppler Effect in light works the same way as it does for sound: Have a longer wavelength (spread out by the mouse's motion). The cat on the right hears a lower-pitched squeak because the waves.Have a shorter wavelength (scrunched together by the mouse's motion). The cat on the left hears a higher-pitched squeak because the waves.(towards the left) are are scrunched together, while those behind are Because the mouse is moving, the sound waves The sound wave ('squeak!') moves outward spherically fromĮach point of emission. The mouse emitted a squeak when it was at the location of each of the The mouse is moving towards the left towards the first cat and Two cats are sitting between a windup mouse toy that emits an electronic direction of motion (together or apart).relative speed of the source & observer.The amount of the shift and its sign depends on Waves and the observer are moving either towards or away from each other. The observed wavelength of a wave will change when the source of the To convey some idea of the scale of the problem, most people can walk atĪ speed of about 1 meter/sec, while a car moving 65 MPH is moving at a

New techniques can achieve The current state-of-the-art is 3 meters/sec.The challenge is to measure the Doppler shifts of the lines with Sun: 13 meters/sec at 0.0052 AU from the C-of-M.Jupiter: 13 km/sec at 5.2 AU from the C-of-M.Of the star-planet system, and thus it has a very slowĮxample: Orbital Speeds of the Sun & Jupiter The greater mass of the star put it close to the center-of-mass Measuring the orbital motions provides an estimate of the unseenįorm of Kepler's Third Law of Planetary Motion. The wobble moves the star away from the Earth. Star's spectrum shifts towards the red when.When the wobble moves the star towards the Earth. Star's spectral absorption lines shift towards the blue.The center of mass of the star-planet system.ĭoppler Wobble or Radial Velocity (RV) MethodĮffect to detect the orbital motions of the wobbling star. Viewed from afar, the star will appear to wobble about Mass, but much closer to the center of mass at The star also orbits around the planet-star center of.Planets orbit on ellipses with the center of mass.Gravitational microlensing of a background star by the planet.Orbital motions ('wobbling') of the star because of the planet's gravity.Stars, which causes a characteristic drop in brightness. Observe the transits of planets across the disks of their parent.Take pictures of planets orbiting other stars.Has intelligent life arisen on other planets?.Are such solar systems like ours or different?.Are there solar systems around other stars?.The question of the existence of other planets beyond the solar system, Many Jupiter-sized planets close to their parent stars.Doppler Wobble (Radial Velocity) Method via the Doppler Effect in orbits.Key Ideas: Search for planets around other stars.

Astrometry vs. doppler method