We have just seen the first image of a black hole, the supermassive black hole in the galaxy M87 with a mass 6.5 billion times that of our sun. But what is that image really showing us? This is an awesome paper on the topic by J.P. Luminet: Image of a spherical black hole with thin accretion disk Astronomy and Astrophysics, vol. 75, no. 1-2, May 1979, p. 228-235 https://ve42.co/luminet Continue reading
Black holes have been mysterious and elusive — until now. Astronomers using the Event Horizon Telescope (EHT) have, for the first time, photographed one. Continue reading
How do astronauts survive the deadly radiation of deep space? NASA is still figuring out how to protect astronauts from cosmic radiation — like plastic shielding and magnetic deflectors. Continue reading
he useful glare-blocking properties of polarized sunglasses are well-known to just about anyone who goes outside. What isn’t so well-known is how they reduce glare in the first place. That answer is deceptively complicated! Continue reading
UV cameras expose a hidden world and reveal the incompleteness of our perception. In summary, ultraviolet light interacts differently with matter for a number of reasons: 1. Some pigments selectively absorb UV so they may appear white in the visible but dark in the UV. Continue reading
This interesting resource shows what happens when a light bulb is placed in a microwave oven. Click on the source to get a video and Steve Spangler’s explanation of how this works.
Source: Microwave Light Bulb – SICK Science | Science Experiments | Steve Spangler Science
MIT Media Lab researchers have created a new imaging system that can acquire visual data at a rate of one trillion frames per second. That’s fast enough to produce a slow-motion video of light traveling through objects. Continue reading
Watch as chlorophyll transforms from an intense green to a bright red colour as UV light is
absorbed and photons are emitted from the solution.
Chlorophyll is the green pigment essential for photosynthesis. It is found in all plants and readily absorbs light in the range of
600–700 nm. Upon excitation by light, an electron in a chlorophyll molecule is moved to a higher energy level, called an excited
state. The exciting source in this demonstration is the UV black light. In fluorescence, when a light source is shined on a material,
a photon is absorbed. From this excited electronic state, the electron naturally wants to relax back down to the ground
state. As it relaxes back down to the ground state, it emits a photon. If the emitted photon’s wavelength is in the visible portion
of the spectrum, we observe a colourful, glowing effect. Emission of this form is termed fluorescence. This process is practically
instantaneous so the fluorescence is observed as soon as the exciting source is present, and it disappears as soon as the exciting
source is removed. The fluorescent glow is brighter than the colour of the solution seen under normal visible light because
light is being emitted from the solution, not just transmitted through it. When a flashlight is shined directly into the solution,
a slight red fluorescence can be observed around the edges of the flask. This is due to a very small amount of light generated by
the flashlight in a range which will excite the chlorophyll molecules.
Click here to download the entire activity…