High School Teachers 2006

Questions to answer How can we understand if what we see is a star or a planet?(or something else…..) Can you imagine an easy way to find how far a star is from the earth? Can you understand what the materials are in the star from that distance? If there are stars like our sun is it possible to have planets like our planet? Are We Alone?

How can we understand if what we see is a star or a planet How can we understand if what we see is a star or a planet?(or something else…..) Planets If we consider the Earth as the centre of the solar system then the sun and the planets are in the same plane. So the planets during the night must be in the same trajectory as the sun in the day. But….. How can we distinguish the planets from the stars even in this narrow plane?

Stars In the case of a planet the cone of light in the surface of the upper atmosphere is about a few hundred meters but in the case of a star is only a few cm. So the atmospheric turbulence may affect the image of the stars but not those of the planets. That is why the stars twinkle at night but the planets do not.

Can you imagine an easy way to find how far a star is from the earth? practically For the Sun Intensity of light Distance For a star (like our sun) We can imagine that a star looks like a light of 100W at a distance of 10Km Intensity of light Distance

Exact but only for near objects Exact methods of finding distances Exact but only for near objects Parallax Only for distances up to 200 light years Star distance Astronomical unit =1AU r

Other methods…….. As far as we can see v =H D Standard Candles Example For this type of stars we can evaluate with great accuracy the absolute magnitude by change of the period of luminosity Novae 6 million light years Supernovae 30 million light years Cepheid 60 million light years Hubble's Law 1billion light years v =H D

The analysis of light is a common phenomenon Can you understand what the materials are in the star from that distance? The analysis of light is a common phenomenon

Spectroscopy Continuous spectrum Emission spectrum Absorption spectrum Hot gas Emission spectrum Cold gas Absorption spectrum

Each element is responsible for a different set of absorption lines in the spectrum so the spectrum indentifies the element like the fingerprint indentifies the human.

Spectroscopy mechanism Cold gas

The absorption spectrum of the sun

UFO Sightings Map: Western Hemisphere If there are stars like our sun is it possible to have planets like our planet? Are We Alone? What is this; UFO Sightings Map: Western Hemisphere If you don’t believe….

MATHEMATIC CALCULATION THEORIES panspermia Exogenesis MATHEMATIC CALCULATION DRAKE EQUATION N is the number of civilizations in our galaxy with which we might expect to be able to communicate at any given time and R* is the rate of star formation in our galaxy fp is the fraction of those stars that have planets ne is average number of planets that can potentially support life per star fl is the fraction of the above that actually go on to develop life fi is the fraction of the above that actually go on to develop intelligent life fc is the fraction of the above that are willing and able to communicate L is the expected lifetime of such a civilization Current estimates of the Drake equation parameters N=0,000008

SETI (Search for Extra-Terrestrial Intelligence) Direct search Arecibo message SETI (Search for Extra-Terrestrial Intelligence)

Multiple planet systems OBSERVATIONS OF EXTRASOLAR PLANETS Multiple planet systems There are currently 45 known planets in 19 multiple planet systems Single planet systems There are currently 144 known planets in single-planet systems GQ Lupi on 25 June 2004 with the adaptive optics instrument

MISSIONS FOR EXTRASOLAR PLANETS SEARCHING NASA Kepler Mission (2008) ESA Darwin (2015) Kepler spacecraft Darwin