-The starting point of the Universe is thought to be the Big Bang, a rapid expansion at
the light speed of matters, evidence by universe expansion explained in Hubble’s Law and
Microwave Background Radiation. The universe contains three main component; Dark Matter
(26.8%), Dark energy (68.3), and Ordinary Matter (normal element) (4.9%). Two of the largest
type of astronomical body are; Galaxies and Nebula. Galaxy is the system of billions of star
gravitationally bond together, while Nebula is just cloud of interstellar gas and dust.
In astronomy, there are 3 main unit of length: Astronomical unit (AU), Light years and
Parsec. Astronomical Unit is the distance between Earth and Sun, which approximately 1.5
×1011 m. Light-years is the distance which light can travel in 1 Earth-years therefore would be
equal 60(second per minute)*60(minute per hour)*24(hour per day) 365.25 (day per year)*3×108
(m/S) = 9.5×1015 m. One parsec is the distance at which one astronomical unit subtends an
angle of one arc second which would be around 3.0857×1016 m or 3.26 light-years.
The study of astronomy can be tracked be to ancient time. The earliest record of
astronomical phenomenon is belong to Sumerian, a civilization in Mesopotamian era. While not
the first civilization to study astronomy, however with numerous philosopher, ancient Greek had
contributed many idea to astronomy. One of the ideas is the orbiting around the center of stars
and planets. Although proposed by Aristarchus that the Sun is center of the system, most
philosophers believed that Earth is the center of universe. Another civilization that have influent
on astronomy are Arabians (or Muslim community) evidence by many of star name which are
Arabic. In the modern time, one of the well-known astronomer is Johannes Kepler who propose
Kepler’s law of planetary motion.
The brightness of star is ranked by magnitude scale, the higher the magnitude, the
dimmer star. There are two type of magnitude apparent magnitude, the brightness appear on
Earth, and absolute magnitude, the assumed brightness at 10AU from each star
Galaxies are classified by its shape as it the only thing we can actually observe. There
are 3 types and 1 Subtype of galaxies; Spiral galaxies, Elliptical galaxies and Irregular galaxies.
Spiral can also be divine into Normal and Barred. Generally, there are 3 parts of galaxies that we
can see, Bulk or center of the galaxies, Spiral disk or Spiral arm, and Halo. While all 3 can be
spotted in Spiral galaxies, only Bulk and Halo are in Elliptical. However in irregular galaxies there
are no distinctive shape as each part. Our Milky Way is Barred Spiral galaxies.The solar system is born when the formation of the sun begin which was around 5
billion years ago. Astronomical Object can be separated in to 4 part, inner planets, asteroid belt,
outer planets, and comet or Oort’s cloud from the sun to outer space respectively. Planets in
solar system must have 3 characteristics 1) orbiting around the sun, 2) shape is stable due to its
own gravity and 3)has cleared the neighborhood around its orbit. Planets can be classified in to
2 types, rocky planets, Solid surface with metallic Core, and gas planets, liquid or no surface
with stone or ice core. The sun has about 7 layer of structure and atmosphere, while the core,
where nuclease fusion occur, is around 15 million degrees Celsius, the hottest layer is believed
to be the Corona, the outer part of the sun’s atmosphere, at 20 million degrees Celsius.
-Planets size from biggest to smallest: Jupiter, Saturn, Uranus, Neptune, Earth, Venus,
Mars, and Mercury.
-Planets with moons; Mars (2 moons), Earth (1 moon), Jupiter (67 moons), Saturn (62
moons), Uranus (27 Moons), and Neptune (13 Moons)
-Planets with rings; Jupiter, Saturn, Uranus, Neptune.