Lecture 1: Hisotry of Astronomy, Lecture notes of Astronomy

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History of

Astronomy

Astronomy 1100

LECTURE 1

I. SCIENTIFIC METHOD:

D e f i n i t i o n :

STEPS INVOLVED IN THE SCIENTIFIC METHOD:

A systematic technique to scientific research that involves formulating hypotheses, conducting experiments or observations to test a hypotheses, and drawing conclusions based on evidence. If there are no contradictions are found, it is physical law. Observation : In this stage, a researcher must first determine what they will study. AKA Theory Construction. Once the topic has been chosen, a review of existing literature or research must be done in order to gain insight into what has been tested and what questions remains unanswered. This in return will help formulate a research question.

2. Question : Once background research and observation were made, the next step is asking a scientific question that can be tested, measurable and defined. Independent Variable: AKA The cause, a variable that you manipulate or control in an experimental study to test the effects on the dependent variable. Explains Dependent Variable: AKA The effect, a variable that “depends” on the independent variable. It is the variable that is being measured in response to changes in the independent variable.

II. SCIENTIFIC THEORY III. SATELLITE

D e f i n i t i o n :

An explanation of the natural world that is based on a body of empirical evidence through observation, experimentation and reasoning (how or why things work the way they do). Predictions that are testable and falsifiable. The Earth’s mass exerts a gravitational force that extend into space. Since satellites have high orbital velocity, it is attracted to to the gravity on Earth => helps to keep it in orbit and circle around Earth without dropping to the ground (never-ending rotation). Used to study celestial objects and phenomena in space.

Bigger mass of the object = stronger gravitational force. Farther apart between objects = weaker gravitational force. IV. PHYSICS Satellites usually orbits in an elliptical or sometimes circular. The Moon is also Earth’s source of satellite. Newton’s law states that every single mass in the universe attracts each other with a force called Gravitational Force. III. SATELLITE Depending on the velocity of a satellite, if too low, it will not achieve a stable, successful orbit around Earth and will instead crash back to the surface in a ballistic trajectory.

N e w t o n ’ s L a w o f U n i v e r s a l

G r a v i t a t i o n :

The strength of gravitational force between two objects depends on their Mass and Distance.

Mass 1 Mass 2

o ------> <------o

Distance

VI. CELESTIAL SPHERE VII. PARALLAX

D e f i n i t i o n :

In Ancient times, people pictured Earth surrounded by a dome. Celestial sphere, a transparent sphere with infinite radius surrounding Earth. Planets, stars, Milky Way, Sun and Moon are on the surface of the celestial sphere. Used as a reference system to map objects in the sky. Used to calculate distances of stars. By holding your finger between your eyes, alternate by closing each eyes. Finger will appear to have jumped to a different spot on the background. In astronomy, two different points in Earth’s orbit is used to estimate the distances of stars.