background preloader


Facebook Twitter

Absorption and Emission. Continuum, Absorption & Emission Spectra A given atom will absorb and emit the SAME frequencies of electromagnetic (E-M) radiation.

Absorption and Emission

A gas of hydrogen atoms will produce an absorption line spectrum if it is between you (your telescope+spectrograph) and a continuum light source, and an emission line spectrum if viewed from a different angle. If you were to observe the star (a source of white light) directly, you would see a continuous spectrum, with no breaks. If you observe the star through the gas (telescope to right of gas cloud, points towards star through cloud), you will see a continuous spectrum with breaks where specific wavelengths of energy have been absorbed by the gas cloud atoms and then re-emitted in a random direction, scattering them out of our telescope beam. We call this an absorption spectrum (continuous + dips). Thanks to Mike Bolte (UC Santa Cruz) for the base contents of this slide. Spectra of Gas Discharges. Below are images of the spectra of the lines of each element which would be observed as emission lines in an electrical gas discharge.

Spectra of Gas Discharges

The images are screen shots of an applet - originally written by John Talbot - which reads in a file with wavelengths and intensities and makes a colourful representation of the spectrum. All data are taken from the NIST Atomic Spectra Databaseby the National Institute of Standards and Technology, Gaithersburg, MD., U.S.A. The line intensities are as given in these tables, to give an impression of the relative line strength. However, it must be emphasized that the spectra shown may not correspond to the discharges we see in the form of various street lamps, because the excitation conditions (electric voltage, temperature, density) may well be different ... The Applet with user control of all parameters is here. The Multispectral Sun. Your eyes tell you that the Sun obviously delivers energy to Earth in the form of visible light.

The Multispectral Sun

If you think about it a bit, especially in terms of the choices you make about UV-A and UV-B protection when you shop for sunscreen or sunglasses, you'll also realize that you know that the Sun also bathes our planet in ultraviolet "light" or radiation. The Sun, in fact, emits radiation across most of the electromagnetic spectrum... from high-energy X-rays to ultra-long wavelength radio waves. Let's take a look now at this multispectral Sun and the energy it emits.

Later in this week we'll see what happens to these different types of energy when they reach Earth. Electromagnetic radiation from the Sun is the main source of energy that drives Earth's climate system. Is Light a Wave or a Particle? It’s in your physics textbook, go look.

Is Light a Wave or a Particle?

It says that you can either model light as an electromagnetic wave OR you can model light a stream of photons. Stilkonkurranse: Cassiniforsker i én dag. Cassini-forsker i én dag er en stilkonkurranse for elever i alderen 10-18 år som nå er åpen for påmeldinger.

Stilkonkurranse: Cassiniforsker i én dag


Guide to Space. By Matt Williams on April 24, 2008 The Solar System: Outer Space:

Guide to Space

Using space in education. Hjem - Norsk Romsenter. Bring verdensrommet inn i klasserommet. Myter og sagn om stjernebildet Orion. Om vinteren er Orion lett å få øye på.

Myter og sagn om stjernebildet Orion

Ta utgangspunkt i de tre stjernen som utgjør beltet. De er som perler på en snor og den midterste av stjernene i beltet heter Alnilam, og det betyr ”perlerad”. Den nordligste av de tre stjernene heter Mintaka som betyr ”kjempens belte”. Den sørligste av de tre stjernene er en dobbeltstjerne som heter Alnitak. Fra beltet henger sverdet, en rad svakere stjerner. Orions belte er et godt utgangspunkt for å finne andre stjerner på vinterhimmelen. Orions høyre skulder er den rødlige stjernen Betelgeuse.

Et stykke under beltet finner du Rigel, en blåhvit stjerne som utgjør Orions venstre fot og Saiph som danner hans høyre fot. Foran Orion, halvveis til Tyren er det en bue av svake stjerner. Orion var ingen vanlig dødelig. Rødfarge på himmelen og dugg på blomster og blader En gang truet Orion med å drepe alle dyrene på jorda, fordi han mente at han var så flink en jeger. Cosmic_Calendar-wikimedia commons. Science Explained: Where Did the Big Bang Happen? Where's the Center of the Universe? Timeline of the universe after the big bang (Image Credit: NASA) The Big Bang happened some 13 billion years ago.

Science Explained: Where Did the Big Bang Happen? Where's the Center of the Universe?

Before this time, as best we can tell, there was no time (or space, for that matter). If there was anything before the Big Bang, we can’t study it or say anything about it due to the constraints placed on us by the physics of our universe. In short, we can’t go back to a time before the Big Bang. So we can’t know what was there. But what about the Big Bang itself? This is actually a pretty common question. However, what many people don’t realize about the Big Bang is that it was not matter exploding into empty space. When the Big Bang happened, everything was in one location.

To be absolutely clear, space was literally growing everywhere. And here’s the thing: Space is still stretching out in much the same manner.