Take-Home Message & Topic Sentence Outlines samples
THM: Solar sails offer a fuel-less propulsion method that is actively
being research for applications in unmanned spacecraft and
- Solar sails are a space propulsion method that
utilize radiation pressure emitted from a star instead of a fuel.
- Radiation pressure is a small force that acts upon
anything exposed to electromagnetic radiation due to the momentum
imparted by photon collisions.
- Due to the weakness of radiation
pressure, large sail structures are required for any meaningful
- A Japanese spacecraft, IKAROS, has already
been launched and demonstrated the use of solar sails as a propulsion
- Solar sails are being looked at for
additional usage in probes and as a means to decelerate and deorbit
THM: Doppler cooling, and laser cooling as a whole, allows cooling of
samples to allow very precise measurements and interactions.
- Doppler cooling is a form of laser cooling that
leverages specific frequencies of lasers to cause atoms to emit
photons and thus lose kinetic energy (reduce in temperature).
- Utilizing a specific frequency light, atoms have their
electrons excited based on their movement thanks to the Doppler
effect altering the light's frequency.
- Doppler cooling has a theoretical minimum reachable
temperature known as the Doppler temperature, at which point momentum
is no longer lost due to collisions.
- Doppler cooling is used in technologies such as
precise atomic clocks and magneto-optical traps.
- Alternative methods of laser cooling such as
Sisyphus cooling and optical molasses have been developed that
overcome the Doppler temperature limit of Doppler cooling.
THM: Auroras are a beautiful spectacle of light in nature that is the
result of a complex interaction of earth's magnetic field and our
- An aurora is a naturally occurring display of light
found near the magnetic poles due to interaction between solar winds
and earth's magnetic field.
- Auroras are typically found in the auroral zone, a band
approximately 5 through 15 degrees away from Earth's magnetic poles.
- Auroras are thought to be caused by ionization of the
atmosphere by solar winds guided by the magnetic fields, though the
full reason is not entirely known.
- The auroras themselves can take on many colors and
are divided into discrete (curtain-like) auroras and diffuse auroras.
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