Brightspace Notes

Chapters and slideshows

Slideshow:

Models:

• Geometric model 

• A branch of math and geometry that studies methods and algorithms for the mathematical description of shapes

• Was based on an idea for Aristotle and refined by Ptomely

• Heliocentric model 

• Prompts the idea that the sun is the center of the solar system

• Doesn’t explain the retrograde motion problem

Chapter 7:

• Because there is quite literally a big gap between what we see and what the stars are actually doing, there is oftentimes a large delay in things

• Since in astronomy, people work with large distances, a new unit of measurement called an “astronomical unit (AU)” was created. Which is the average distance between the Sun and the Earth (~150M km)

• Once past mars, we will encounter the asteroid belt1, and after that are the rest of the planets

• The next nearest star to Earth after the Sun is actually part of a group of three stars called Centauri system

Despite it being called the “nearest”, it is not near at all. If you were to have a phone call with someone there, it would take around 8.5 years to get the message across, pursuing it at the speed of a radio signal.

• When the outer layers of the star are pulled into the center by gravity, the outer material crashes into the inner core. Thus causing both the temperature and pressure to increase and the star to explode. This train of events is known as a supernova2

• Star clusters3 can occur in two broad types. Open and globular clusters

Open:

• The younger star groups in the galaxy

• Contains a few hundred to a few thousand stars

Globular

• Contains hundreds of thousands of stars

• They are drawn together in a spherical formed by the star’s gravity

Just as there are star clusters, there are also galaxy clusters. For example, the cluster that the Milky Way is in, (the Local Group,) has around 20 galaxies, and is a part of the Local Supercluster.

• Light is a form of energy that travels in waves, which is also called electromagnetic radiation

• Different lights can differ in wavelength

• A star’s band of color appears as a series of dark lines, which are also called spectral lights

• Using the knowledge of spectral pattern, they concluded that galaxies were moving apart, which was later known as spectral shifting

Keywords:

Nuclear fusion — the process in which the nuclei of atoms fuse together and form larger atoms

1Asteroid belt — a region of rocky debris that forms a ring all the way around the Sun

• Roughly around 3 AU

Binary system — a system with two stars

2Supernova — when a star explodes

3Star clusters — distinct group of stars

Dark matter — refers to matter in the universe that is invisible as it does not interact with any type of radiation (even light)

Spectroscope — an optical instrument that, like a prism, separates light into its spectral colors