Spectroscopy Auguste Comte was a French philosopher who lived from to He was quoted as saying, "There are some things of which the human race must remain forever in ignorance, for example the chemical constitution of the heavenly bodies.
What are the different Astronomical instruments? Astronomical instruments are basically divided into two groups. The first group consists of all instruments that are used for observing celestial objects, such as the telescope and other observational instruments are primarily the radiation collectors emitted by stars, planets, nebulas, and galaxies.
The second group relates to supplementary instruments in use for recording or regulating the data which are received by the observation instruments. Some of the examples of instruments that fit into the second group are instruments that offer a precise standard of time, to find out the brightness of stars, to document their spectra, or to compute the location of stars.
What is the History of Astronomical instrument? The history of astronomical observation dates back to the ancient times. All the older civilizations have some records of studying the celestial skies and measuring to help them with their daily life.
In addition to the, crude water and sand clocksthe time of day was calculated by the direction and length of shadows shed by perpendicular objects such as buildings, pyramids, stone columns. Calculations of the shadow lengths and directions slowly went behind, and the precursor of the contemporary sundial was born.
The most primitive sundial or shadow- clock is Egyptian which was roughly before B.
The habit of performing systematic astronomical observations, and the use of these in the formulation of theory, was invigorated in the third and second centuries B. What are the various astronomical instruments?
A kind of moveable armillary, customized for stellar observation was the astrolabe. At the center of the ring, a rod was pivoted which was equal in length to the ring diameter, carrying sights at either end.
An angular scale emblazoned on the armillary ring depicted the object's height, when aligned on a star or planet. The gnomon and the armillary sphere were the fundamental instruments in ancient days. The gnomon was simply a pointed perpendicular column of known height erected on a flat plane used primarily to show time.
With the direction of the shadow cast at noon, the north-south line was recognized allowing the azimuths angular directions of objects on the earth's surface to be calculated.
By understanding the height of the gnomon, the lengths of the shortest and longest noon shadows observed during the year, the angle of the ecliptic plane the plane containing the apparent path of the sun to the earth's equatorial plane and the latitude of the observer were anticipated. The length of the tropical year was calculated by the time interval between consecutive observations of the longest or shortest noon shadows.
The armillary sphere was probably invented to increase the precision of the results attained by the gnomon and to increase observations to the sun and the star.
The most ancient armillary, a solar instrument, comprises of two bronze concentric rings, few feet in diameter, mounted in the plane of the meridian.
The inner ring turned within the outer ring and carried two small pegs mounted at opposite ends of a diameter. The inner ring was attuned until the shadow cast by the upper peg fell on the lower peg. An angular scale on the outer ring, alienated into degrees, showed the meridian altitude of the sun.
Ancient astronomers may have used this type of armillary, instead of a gnomon, to choose the angle of the ecliptic plane. One more type of solar armillary, with which ancient astronomers was probably familiar, might have had a single ring mounted in the plane of the celestial equator.
The length of the tropical year can be determined with such an instrument since the shadow of the upper half of the ring falls on the inner surface of the lower half when the sun is at either equinox.
Armillaries designed for stellar observation, were very much complex. They consisted of a number of rings, the largest of which was mounted on a stand and attuned to rest in the plane of the meridian.
Ptolemy was the final Greek astronomer of ancient times who made a good contribution for the development of astronomical instruments in second century. Ptolemy, in his astronomical documents, stated regarding three new instruments: Since it was initially used, the plane of the quadrant was adjusted to lie in the plane of the meridian.
Vertical alignment was shown by a plumb-bob poised from the quadrant's center. Pivoted from this center was one end of a movable rod just about equal in length to the radius of the quadrant.
Sights mounted on the rod allowes observations to be made of stars and planets as they crossed the observer's meridian, and an angular scale emblazoned on the margin of the quadrant denoted their meridian altitudes. However, nobody knows whether Ptolemy really constructed such an instrument or not.Explain how astronomical instruments help astronomers determine the composition, temperature, speed, and rotation rate of distant objects.
Explain the properties of stars in the diagram located in the “What is a Hertzsprung-Russell diagram?” section in Ch. 12 of The Essential Cosmic Perspective. Jan 30, · The simplest way is "color index".
By taking pictures of a star through two different color filters and comparing the brightness in each, temperature can be found. If the image is brighter through a red filter than green, for example, it's cooler than another star in Status: Resolved. It is one of the most useful devices in astronomy, because it allows astronomers to determine the chemical composition of planets and stars, as well as to indicate the speed and direction of a .
Astronomical instruments are basically divided into two groups. The first group consists of all instruments that are used for observing celestial objects, such as the telescope and other observational instruments are primarily the radiation collectors emitted by stars, planets, nebulas, and galaxies.
Furthermore, technological advances in astronomical instruments in the 20th century permitted Hubble and others to view far beyond the Milky Way. Today, with the knowledge of atomic structure, spectral analysis, and remote observational satellites, opportunities to acquire new information seem limitless.
In this paper I will address how astronomers determine the composition, temperature, speed, and rotation rate of distant objects. I will briefly explain the properties of stars in the H-R diagram from Chapter 15 of the course textbook “The Cosmic Perspective”.