Astronomy Definition and 832 Threads

Astronomy (from Greek: ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates outside Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole.Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Babylonians, Greeks, Indians, Egyptians, Chinese, Maya, and many ancient indigenous peoples of the Americas. In the past, astronomy included disciplines as diverse as astrometry, celestial navigation, observational astronomy, and the making of calendars. Nowadays, professional astronomy is often said to be the same as astrophysics.Professional astronomy is split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects. This data is then analyzed using basic principles of physics. Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. These two fields complement each other. Theoretical astronomy seeks to explain observational results and observations are used to confirm theoretical results.
Astronomy is one of the few sciences in which amateurs play an active role. This is especially true for the discovery and observation of transient events. Amateur astronomers have helped with many important discoveries, such as finding new comets.

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  1. J

    Astronomy time required to capture exposures problem

    Homework Statement If you have a large telescope that has a 5 meter diameter with a field of view of 1 foot by 1 foot, and a small telescope with a diameter of 1 meter with a field of view of 1 degree by 1 degree, and your trying to take images of 30 quasars that has a limiting visual magnitude...
  2. alw34

    Is this possible "giant planet' a hot topic in astronomy?

    Downloads are approaching 300,000 so somebody is interested. The 'planet', if it exists, is expected to have an 'appreciably eccentric' orbit. Is there any inventory of how many teams might be searching for this object?? EVIDENCE FOR A DISTANT GIANT PLANET IN THE SOLAR SYSTEM Konstantin...
  3. C

    Can Astrophysics Students Improve Their Math Skills for Success?

    I'm an astrophysics student. Wish I could math better. Good luck to you all in your studies.
  4. J

    Estimating Star Counts from Density Laws

    Homework Statement (This is a long problem but I think the question is not hard.) Determining the star density from star counts is tough, but estimating counts from a density law is simpler. In practice, this method of fit-ting observed number counts to an assumed density law is becoming a...
  5. pioneerboy

    Nobel prize for Brown and Batygin?

    If hypothesised planet nine is really discovered in the outskirts of our Solar system, will M. E. Brown and K. Batygin have a chance to win the Nobel prize in physics or is this too much of an old hat for the Nobel-commitee?
  6. F

    Calculating Angle Between Ecliptic and Horizon for Observer at 18 Degrees North

    Homework Statement Which is the angle between the ecliptic and the horizon in the moment that the point of Aries is hiding for an observer whose position is 18 degrees north? 2. Homework Equations None The Attempt at a Solution The first thing I have tried to is to do a drawing of the...
  7. Clusters Of Galaxies - Professor Carolin Crawford

    Clusters Of Galaxies - Professor Carolin Crawford

    Public lecture on aspects of galactic clusters. Covers physical characteristics, observation methods, dynamics and evolution, interactions within clusters, types of components (galaxies), dark matter, gravitational lensing.
  8. Rotation in Space - Professor Carolin Crawford

    Rotation in Space - Professor Carolin Crawford

    Public lecture on aspects of rotating astronomical objects. Covers planetary and stellar rotation, protoplanetary discs, accretion discs and galactic rotation curves. Mechanisms and observation methods.
  9. G

    Exploring the World of Astrophysics: A Scientist's Journey to a PhD in Physics

    I just want to say hi. I love physics. Astrophysics in particular! I'm a returning undergrad to an undisclosed university. I plan to get my PhD in physics as well. I'm on here to get guidance in that. I would also like to discuss math and physics problems as well. Looks like I came to the right...
  10. J

    Angular distance in globular clusters

    Homework Statement Go to the following web site: http://www.astro.utoronto.ca/~cclement/cat/listngc.html This is the portal to a large on-line catalog of variable stars in globular clusters. Each link is a cluster name and will take you to a simple text page that lists near the top the...
  11. sami_m

    The probable trajectory of the ninth planet in night sky?

    What would be the propable trajectory and position of the ninth planet that has been suggested few days ago (20.1.2016 by Konstantin Batygin and Michael E. Brown) ? if i understood correctly, the exact position of the planet is unknown and has not been evaluated. But by looking this article...
  12. JoAstro

    Two stars with the same mass equals the same luminosity?

    As the Stephan-Boltzmann's Law says, the minimal change in a star's mass would have a massive effect on its luminosity, but can necessarily two stars with the same mass have the same luminosity?
  13. O

    Average time per week early-career academics in the US work?

    Hello. I've got two questions: 1) In the U.S., what's the average time per week that a graduate student doing a PhD in astronomy work? 2) In the U.S., what's the average time per week that a postdoctoral researcher in astronomy work? Thanks in advance for your answers.
  14. S

    Astronomical source extraction in non uniform background

    I have been working with some Herschel images and I am finding it difficult to extract the astronomical sources from the image. The image background is extremely non uniform so i am not able to differentiate between the background and the source. I used some tasks in HIPE like source extractor...
  15. JoAstro

    What Is the Effective Temperature and Luminosity of Star A?

    I am trying to find the temperature of a star given its wavelength in micrometres, but I am not sure if my conversion is right therefore don't know if the answer is correct. Star A has a maximum emission wavelength of 1 μm and Radius 100 Rsun. What is its Effective Temperature and Luminosity...
  16. JoAstro

    Stargazing How to calculate the amount of light a telescope collects?

    Having the unaided eye's pupil to be 6.4mm and the diameter of a telescope 8-inches, how can I calculate the amount of light the a scope collects over the human eye?
  17. jamalkoiyess

    Astronomy/Astrophysics subdivisions

    hello, can anyone give me what they know about astronomy and astrophysics subdivisions in masters degrees and Ph.D.s . thank you
  18. W

    Yet another read-my-REU-essay-please thread

    Hi guys! Like the title says, I'm applying for 10 astrophysics-related REUs, and I'm a frosh, so I have few other people to ask for guidance. Please let me know if this is a good baseline to add to. Thank you all in advance!Sitting in the middle of an abandoned lab, late on a Friday night, head...
  19. O

    In astronomy what is the average duration of doing postdocs?

    Hello. I read that in astronomy a PhD lasts an average of 6.1 years. But what about postdoctoral research? In astronomy, what is the average duration of doing postdocs before finally getting a real job? (a job as an astronomer; not reconverting to another field to get a job in this other...
  20. JoAstro

    What's the thermal energy of a helium atom?

    I have this formula "E= 1/2 mv^2" which I don't fully understand. Also, I don't have the values for helium's mass and velocity.
  21. T

    Confusion in Doppler shift equation?

    I'm just trying to build Doppler shift equation for Moving observer and stationary source. I have an problem in a step. I'm attaching a screen-shot please check it and tell me where to this step ( 1 - v/u)^-1 comes from ? Thanks in advance.
  22. M

    Anyone in Honolulu interested in astronomy, etc.?

    Hi! I'm new to the forum, but I'm looking for some people who live in Honolulu who are interested in astronomy, astrophysics, cosmology, etc.. I'm especially interested in clubs/group meets and getting together to view astronomical events. Check out my profile to learn more about me. :)
  23. M

    Exploring the Depths of Astronomy and Astrophysics in Hawai'i

    Hello, all! My name is Marina and I currently live in Honolulu, HI. I'm an ocean engineering major, but my primary interests are in astronomy and astrophysics! I'm hoping to meet a lot of people here that can help me deepen my understanding of those subjects, and maybe even find some people...
  24. R

    Astronomy Non Calculus Astronomy Math textbook

    I am participating in science olympiad just for fun this year, because i have a mild interest in astronomy. I am in the astronomy event, my partner has decided to split the knowledge into math and non-math, and as i will be handling the math I would like a book(or however many) that has...
  25. S

    What are the job prospects for Astronomers in the next 10-15 years?

    Hello all! I am currently a freshman (just finished my first semester) and I need to choose a career path. I have had a burning love and passion for Astronomy/Astrophysics from a very young age but I hear that the job market for Astro Ph.D's is complete and utter dang (pardon my French). I grew...
  26. ujjwal3097

    Programs Physics major vs astronomy major

    I am attending college next year but I am really confused between two majors. I am interested in astronomy and my dream is to pursue my career doing astronomy and I can wait to study astronomy in college. I know that astronomy is completely physics but I am confused whether should I choose...
  27. C

    Signal to noise ratio and uncertainty in magnitude

    1. The problem statement, all variables and given/known dat Show that if you have a signal f and noise σf for a stellar flux measurement, then the uncertainty on the observed magnitude is given by σm = 1.0875 x σf / f Homework Equations (you should use the fact that when ε<<1 then log(1±ε) ≈...
  28. planethunter

    Astro PhD at 34: Chances w/Math & Physics Bkgrd & Good PGRE Score

    I am 34 years old and have a bachelors in math from about 10 years ago. I've also taken 3 graduate physics courses throughout the years. I work full time as a systems analyst, and have been doing this type of work since I graduated from college in 2005. I also have an MBA. I’m wondering, with...
  29. Astrodent

    How many stars we can see from Earth?

    Greetings, Hi, I am new member of Physics Forums. Here is my question: How many stars can we see from Earth? and also If you know, How far can we see? Thanks!
  30. GiantSheeps

    Schools Schools with astronomy, observatory, and planetary science

    Hi! So I've begun the process of looking at colleges now and I really would like to go to a school in the US or Canada with an astronomy major, an observatory of its own, and some sort of planetary science program. I've made a list of the schools that I've been able to find with those things...
  31. K

    Flat Rotation Curve Astronomy Question

    I've been struggling with part (a) of this question. I'm not quite sure what the relation is. Any help is greatly appreciated! Thanks! Consider a spiral galaxy with a “flat” rotation curve beyond the central 2 kpc. a. Derive the general relation giving the orbital period, P, of a star (or...
  32. MidgetDwarf

    Introductory Astronomy or Astrophysics book

    Interested in learning about Astronomy/ Astrophysics. I do not know anything besides the planets, and apparently I learned today that Asteroids are rich in metals.?? I am looking for a book that is introductory, but is not to easy. I have taken a course in freshman calculus based mechanics and...
  33. S

    Difference between Cosmology and Astronomy

    Well I was just wondering that what exactly difference between Cosmology and Astronomy...?
  34. Diego Fernandez

    Ideas for Physics project? IB IA on Astronomy

    Good day :smile: For quite some time now, I've been thinking about what I should make my Internal Assessment for the IB course in physics on. The main objective of the IA is to find and prove a mathematical relationship between an independent and dependent variable. A very, very, simple example...
  35. Ravyan Asro

    Pros and cons for a career in stellar astronomy

    I am really interested in learning more about the space and the universe. And studying about stars interests me the most. So, I have decided for a career in stellar astronomy. However, stellar astronomy is a very huge field of space science and a rarely chosen career. I have a thousand of...
  36. J

    Calculating Jean's length for neutral hydrogen cloud

    Homework Statement What is the Jean's length in parsecs for a typical neutral hydrogen cloud, which has a density of n(H I) ~10^8 atoms/(m^3) and a temperature of 100K? Homework Equations jean's length = sqrt[(15*K*T)/(4pi*G*u*p)] where: 'K' is the Boltzmann constant 'T' is the temperature of...
  37. J

    What is Imaging Science and How Does it Impact Astronomy and Planetary Science?

    I am a sophomore at RIT studying imaging science, which is essentially a major dedicated to the engineering and development of imaging technologies. i.e. MRIs, lasers, telescopes---anything that involves light. I love my major and plan to use it to pursue a career in astronomy and planetary...
  38. Klashta Neali

    I choosing a career in physics to pursue

    I am only in grade 10 but stupid Careers course says I have to choose a career to do a summative study on. I want to choose something that I might go into but I can't choose. The NOC list for "Physics and Astronomy" is very long--I deleted the ones I am not interested in: aerophysicist...
  39. H

    Python Python 2.7 on Windows installation for Astronomy

    Hello people i know this program is better to use on Linux, but for personal reasons i can't change to Linux OS. So I'm having a little problema on how to use python and install the modules of astropy, ipython, I've already installed pip but i have a error on python shell that says: Error...
  40. Kelson Adams

    Use 3D laser scanning to map Outer Space?

    Mobile, airborne, and terrestrial 3D laser scanning gives an unprecedented amount of data to companies, organizations, and governments. However, I am wondering whether or not 3D laser scanners have ever been used in astronomy, astrophysics, and in astrocartography... If they haven't, I believe...
  41. O

    Schools Which are the best American universities for astronomy?

    Hello. I'm a French student and I'm planning to go to the United States for a graduate program in astronomy. When I will arrive in the U.S. I will begin by the first year of graduate. Then I will pursue with a Ph.D. and some postdoctoral research. I would like to know which are the best...
  42. G

    K Corrections: Explaining Fluxes in 250μm (Janskys)

    So I'm trying to k-correct some fluxes in 250μm (janskys) using the M82 template found here and the relevant equations found here (I also have the transmission filter function). The template is normalised to 5500 A and doesn't have a brightness so I fail to see how I can correct my observed...
  43. GiantSheeps

    Stargazing Remote Controlling Truss Dobsonian Telescope?

    Is it possible to rig a Truss Dobsonian telescope like this one so that you can control it remotely from inside of a building while the telescope itself is on the roof of the building? Then is it possible to attach some sort of adapter to the telescope that would allow you to hook up a camera...
  44. H

    Vibrational Continuum in Interstellar Medium: A Closer Look

    Hello everyone, this is my first poster here. I met this problem when I was attending class of interstellar medium, and I was confused by the question.
  45. pioneerboy

    Lunar and Planetary Laboratory vs. Steward Observatory

    Hi there, The University of Arizona has these two institutes (among many others, of course): - Lunar and Planetary Laboratory, LPL for short - Steward Observatory As far as I understand, both are into space research and astronomy. If I wanted to join either one or the other, I would have no...
  46. ujjwal3097

    Programs Physics(astronomy) major vs engineer major

    Hi I am a high school student and currently planning to apply for undergrad studies but i am bit confused in deciding my major.I am pretty sure that I want to major in field related to physics .I am interested in astronomy /astrophysics and also interested in engineering .Please can anyone...
  47. S

    Difference between Astronomy and Cosmology

    What Is the difference between Cosmology and Astronomy..?
  48. GiantSheeps

    Wesleyan for Astronomy and Physics Undergrad

    I'm a junior in high school and I'm starting to look into colleges. The one that I'm most drawn to is Wesleyan University in Connecticut. I want to major in astronomy and physics, perhaps with a minor in planetary science. Wesleyan offers all of those courses, but does anyone know if they are...
  49. W

    Gravitational force confusing question

    I have this question on my practice test that I can't figure out. "Just as one jumps out of a plane what is their gravitational force given that the mass is 70kg." The thing is, for me to use the gravitational force formula I need to masses. The test only has the one. Am I missing something? Am...
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