The following was prepared by Christopher Palma, The Pennsylvania State University The term astronomy is definitely older than astrophysics. Archaeology vs. Anthropology up Environmental Science vs. News Penn State Inservice Opportunity. The Unknown Moon. The Coal and Energy Unit.
How do salmon know where to return to spawn? What are the impacts of climate change on water resources? How much water does it really take to grow almonds? The most important tool to decode the universe is the electromagnetic spectrum. Topics such as dark energy, dark matter, and gravitational waves fall under modern astrophysics. Let us now look at some events that changed the face of this subject.
I am going to share ten major turning points that took astrophysics to the next level. These events shaped the subject and provided a firmer platform among other branches of science.
Astrophysics began when Sir William Wollaston in and Joseph Fraunhofer discovered dark lines now known as Fraunhofer Lines in the spectrum of the Sun as shown below:. When sunlight is passed through a prism, it splits into the colors of the rainbow. These colors are known as the spectrum of the Sun. But when observed, there are many dark lines in it.
These are absorption lines caused by impurities such as calcium, sodium, magnesium, iron, etc. The chief element present in the Sun is hydrogen, and the impurities in minuscule quantities absorb the light coming from the inside at specific wavelengths, resulting in the dark features. We will talk about them in detail in future articles. They classified , stars into 7 major categories based on their spectrum. The system, known as the Harvard Classification Scheme , changed astrophysics and is still used today.
It again showed the importance of the field of spectroscopy in astrophysics. Back around , the source of stellar energy was a complete mystery. He published a paper by the name The Internal Constitution Of Stars in which he talked about this hypothesis. This was a great landmark in the development of astrophysics as it laid the foundation for stellar evolution.
For a long time, it was believed that the universe contains only one galaxy: the Milky Way. Of course, we had images of other galaxies such as the Andromeda galaxy, the Magellanic clouds, etc… They were believed to be stellar systems inside our own Milky Way. But soon, it was realized that there are many more galaxies in the universe. Astrophysics took yet another important turn with the work of Edwin Hubble.
This was solid proof of the fact that the universe is expanding. The field of radio astronomy was pioneered by Karl Jansky in August At Bell Telephone Laboratories Jansky built an antenna designed to receive radio waves at a frequency of After recording signals from all directions for several months, Jansky eventually categorized them into three static types: nearby thunderstorms, distant thunderstorms, and a faint, steady hiss of unknown origin. He spent over a year investigating the source of the third type of static.
The maximum intensity rose and fell once a day, leading Jansky to surmise that he was detecting radiation from the Sun initially. After a few months of following the signal, however, the brightest point moved away from the position of the Sun. By comparing his observations with optical astronomical maps, Jansky concluded that the radiation was coming from the Milky Way and was strongest in the direction of the center of the galaxy, in the constellation of Sagittarius.
Today radio astronomy is a very important branch of research. It is used to study high energy sources such as quasars. However, the first clues of these exotic objects from the sky came in from the constellation of Cygnus. The constellation is the home to Cygnus X-1 , one of the most powerful X-ray sources seen from Earth. It was discovered in It is a supergiant star that is, by itself, incapable of emitting the observed quantities of X-rays.
Hence, the star must have a companion that could heat the gas to the millions of degrees needed to produce the radiation source for Cygnus X After 2 years of detailed analysis, astronomers surmised that the companion is indeed a black hole.
Cygnus X-1 has since been studied extensively using observations by orbiting and ground-based instruments. As of 2 April , there are 4, confirmed exoplanets in 3, systems, with systems having more than one planet.
The discovery of the exoplanets opened a new window of research in planetary science. It also paved the way to search for extraterrestrial life. The discovery of gravitational waves ushered in a new era in astrophysics. Gravitational waves are produced when two compact objects such as black holes collide with each other. They are quite difficult to detect. For a detailed understanding of gravitational waves and their importance in astrophysics, see the third episode of the Q and A series, What are gravitational waves?
Exactly a year ago, i. Along with detecting the gravitational waves, it was the most remarkable event in astronomy so far in this century. Research is now going on to improve the image quality and photograph more black hole candidates with a larger array of telescopes around the world. We now know what is astrophysics. Let us now learn how it is different from its cousins Astronomy and Cosmology.
Astronomy is the branch of science that talks about motion and relative positions of heavenly bodies. Beginner What is the difference between a "star" and a "sun"?
Beginner How do you measure the distance between Earth and the Sun? Intermediate Why do most moons orbit their planets at the equator? Intermediate If the universe is infinite does that mean there is an infinite number of "me"s?
Intermediate Do asteroids hit the Sun? Beginner At what speed does the Earth move around the Sun? Beginner Which planet is most similar to Earth? How long could life on Earth survive if the Sun stopped shining?
Beginner Are there telescopes that can see the flag and lunar rover on the Moon? Intermediate Can artificial gravity be created in space? Intermediate Why do the planets orbit the sun? Beginner How does the position of Moonrise and Moonset change? Intermediate At what speed does the Earth move around the Sun? Beginner Why is the moon in a different place every night? Beginner Is the Moon moving away from the Earth?
When was this discovered? Intermediate Why is the moon in a different place every night? What's going to happen on December 21st ?
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