OWL Astronomy
Lesson:
Welcome to your Astronomy Owl course! Astronomy is the scientific study of the universe as a whole, and of celestial bodies and the underlying physics governing these bodies. It is in some sense one of the oldest of the natural sciences, having been practiced by even very ancient civilizations, but it is also among the most modernized of the sciences, having extensively exploited both advances in technology and the rise of space exploration. The progress of technology has dramatically improved our understanding of the universe, revealing a richer tapestry than had ever been imagined before.
The planets started out as planetesimals. These particles, drawn together by gravity, began to form the large masses that would become planets. The initial collisions of planetesimals melted the surface of the emergent planets. As the planets grew, radioactive heating melted the interior. There are currently eight planets and one dwarf planet in out solar system, listed in the table below is the planets in their order from the sun on one side and on the other is their size, starting from largest to smallest.
| Distance & Size | |
| Distance | Size |
| Mercury | Jupiter |
| Venus | Saturn |
| Eart | Uranus |
| Mars | Neptune |
| Jupiter | Earth |
| Saturn | Venus |
| Uranus | Mars |
| Neptune | Mercury |
| Pluto (dwarf planet) | Pluto (dwarf planet) |
The terrestrial planets lose energy from volcanoes. They are characterized by craters (caused by falling meteorites), volcanoes (caused by magma and radiation) and rift valleys (caused by magma plumes). An example of a rift valley is Valles Marineris on Mars. The heat inside the core of terrestrial planets is caused by the slow decay of uranium, potassium, and thorium. The terrestrial planets include Mercury, Venus, Earth, & Mars.
So called Jovian planets are named after Jupiter, the largest planet in the Solar System. They are also called the gas planets because they consist mainly of hydrogen, or the giant planets because of their size. These planets usually have complicated system of many moons and often even rings of ice and/or dust. There are four Jovian planets in the Solar System: Jupiter, Saturn, Uranus and Neptune.
The Milky Way is a barred spiral galaxy which forms part of the Local Group. Although the Milky Way is but one of billions of galaxies in the universe, the Galaxy has special significance to humanity as it is the home of the solar system. Democritus (460 BC - 370 BC) was the first known person to claim that the Milky Way consists of distant stars.
The term "milky" originates from the hazy band of white light appearing across the celestial sphere visible from Earth, which comprises stars and other material lying within the galactic plane. The galaxy appears brightest in the direction of Sagittarius, towards the galactic center.
Relative to the celestial equator, the Milky Way passes as far north as the constellation of Cassiopeia and as far south as the constellation of Crux, indicating the high inclination of Earth's equatorial plane and the plane of the ecliptic relative to the galactic plane. The fact that the Milky Way divides the night sky into two roughly equal hemispheres indicates that the solar system lies close to the galactic plane.
The Milky Way Galaxy is about 80-100 thousand light years in diameter, about 3,000 light years in thickness, and about 250-300 thousand light years in circumference. It is composed of 200 to 400 billion stars (exact number not yet known). As a guide to the relative physical scale of the Milky Way, if the galaxy were reduced to 130 km (80 mi) in diameter, the solar system would be a mere 2 mm (0.08 in) in width.
The Milky Way's absolute magnitude, which cannot be measured directly, is assumed by astronomical convention to be −20.5.
During the early ages of the universe, the universe was very homogeneous and the only structure present was small fluctuations in the density of the primordial gas cloud. This gas cloud, primarily made up of hydrogen and helium, was formed in the first billion years after the big bang during recombination. Small fluctuations in the primordial gas cloud are observed in the cosmic microwave background, homogeneous to one part in one hundred thousand, which is an indication of the density distribution of the universe after recombination. Areas with slightly higher density had enough gravitational attraction to overcome expansion of the universe and collapsed into the first protogalaxies.
Examination:
This assignment will be very long, and it will require some outside research. It shouldn't be too difficult, that is, no more difficult than the exam should be! It will begin with a theory, and then a practical. The theory will assess your knowledge of the planets, and the practical consists of putting what you have learned to use. Good luck! Please PM the assignment to Prof. Elizabeth Peevison. Thanks!
Matching: The planets in our solar system are all said to affect a person's personality. Each planet, and the sun, is assigned to a certain celestial birth sign and is said to rule the sign. Please match the following bodies with their appropriate sign or signs. (Note: Some plantes will be used more than once.)
| Mercury | Aquarius |
| Venus | Virgo |
| Earth | Capricorn |
| Mars | Cancer |
| Jupiter | Leo |
| Saturn | Scorpio |
| Uranus | Aries |
| Neptune | Sagittarius |
| Pluto | Taurus |
| Pieces | |
| Libra | |
| Gemini |
Essay: Please state your date of birth, sign and ruling planet. Then describe how this planet is said to affect you and give some examples on how this has proved true. There are billions of stars in the nighttime sky. As the earth rotates, we get a good view of many of them throughout the year. These stars create certain patters and you were introduced to many in Advanced Astronomy with Professor Winters. Some were the signs of the Zodiac and some were members of Greek mythology. Some are members of both such as Cancer, the little crab. He is a member of the zodiac but was sent to distract Hercules as he tried to defeat Hydra, the multi-headed monster. They all can be found in the nighttime sky at various times of the year. Please match the following constellations with the month in which they are best viewed.
- Andromeda
- Cancer
- Centaurus (Centaur)
- Draco
- Hercules
- Hydra
- Leo
- Orion
- Perseus
- Pegasus
- Scorpious (Scorpio)
- Ursa Major
Practical: Please enter the planetarium. Call up and point out your favorite constellation from the list below. Please tell the story of this constellation in your own words. Also mention, elxplain and point out at least two other constellation that are linked to your chosen constellation's story. Choose from the following: Hercules, Perseus, Andromeda, Hydra, Leo, Orion, Pegasus, Scorpius or Cancer
Good Luck!
Professor Seraphine Levenworth