Introduction to Astrophysics
                     INTRODUCTION 
TO 
ASTROPHYSICS
INTRODUCTION
Astrophysics is a branch of space science 
that applies the laws of physics and 
chemistry to explain the birth, life and 
death of stars, planets, galaxies, nebulae 
and other objects in the universe. 
Source: www.space.com
ABOUT ASTROPHYSICS
Astronomy measures positions, 
luminosities, motions and other 
characteristics.  Astrophysics creates 
physical theories of small to medium-size 
structures in the universe.
Source: www.space.com
GOALS OF ASTROPHYSICS
1. NASA states that those goals produce 
three broad questions:
How does the universe work?
How did we get here?
Are we alone?
Source: www.space.com
IT BEGAN WITH NEWTON
While astronomy is one of the oldest 
sciences, theoretical astrophysics began 
with Isaac Newton. 
Prior to Newton, astronomers described 
the motions of heavenly bodies using 
complex mathematical models without a 
physical basis.
Source: www.space.com
NEWTON’S THEORY
Newton showed that a single theory 
simultaneously explains the orbits of 
moons and planets in space and the 
trajectory of a cannonball on Earth. 
This added to the body of evidence for 
the (then) startling conclusion that the 
heavens and Earth are subject to the 
same physical laws.
Source: www.space.com
MILESTONES IN 
ASTROPHYSICS
Because the only way we interact with 
distant objects is by observing the 
radiation they emit, much of astrophysics 
has to do with deducing theories that 
explain the mechanisms that produce this 
radiation, and provide ideas for how to 
extract the most information from it. 
Source: www.space.com
SPECTRAL ANALYSIS
The first ideas about the nature of stars 
emerged in the mid-19th century from 
the blossoming science of spectral 
analysis, which means observing the 
specific frequencies of light that 
particular substances absorb and emit 
when heated.
Source: www.space.com
BIG BANG THEORY
 According to the Big Bang Theory, the 
first stars were almost entirely hydrogen. 
The nuclear fusion process that energizes 
them smashes together hydrogen atoms 
to form the heavier element helium.
Source: www.space.com
MODERN RESEARCH
In practice, modern astronomical 
research often involves a substantial 
amount of work in the realm(s) of 
theoretical and/or observational physics. 
Highly elusive areas of study for 
astrophysicists, which are of immense 
interest to the public, include their 
attempts to determine: the properties of 
dark matter, dark energy, and black 
holes; whether or not time travel is 
possible, wormholes can form, or the 
multiverse exists; and the origin and 
ultimate fate of the universe.
Source: planetary-science.org
REVOLUTION
In the 20th century, Albert Einstein 
initiated a new revolution in our 
understanding of gravity with his general 
theory of relativity. Now it’s estimated 
that what we know about the cosmos is 
doubling every 10 years.
Source: planetary-science.org