What is Astronomy: Definition and 820 Discussions

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. B

    Calculating Luminosity from Brightness: Where Did I Go Wrong?

    Hello, I've been trying to solve for the luminosity of Gliese 581 using its brightness. I've been using the equation below: F = (L/(4*pi*r^2)) I have the flux as the absolute brightness of Gliese 581, which is 11.6. The distance, r, to the star is 1.89210568 × 10^17 meters. However, when I...
  2. evictor480

    Attempting writing. Looking for brains to pick for accuracy.

    Hi I am a want to be writer that has high hopes publishing before I am 70, maybe. lol I have a short story idea that is slowly turning into a small novel and even if it never publishes I would like to keep junk science out of it. I am not sure where to post the thread for it or if this is the...
  3. EpicAll Rounder

    What is Stellar Flux and How Does it Affect Solar Wind?

    I have a little problem about Stellar Flux. I've searched google and bing for info but to no avail. Please help me understand Stellar Flux. Thanks, Epicall Rounder
  4. S

    Energy Required to Launch a Geosynchronous Satellite

    Hi all, This question is for an assignment due Friday. My friend and I spent the better part of an hour on it and are thoroughly stumped. Any help is much appreciated! 1. Homework Statement Calculate the energy required to put a satellite into geostationary orbit. (note that no mass is...
  5. E

    What is a Good Masters Thesis for Astronomy?

    Good day! I am currently a freshman at a master's course in astronomy as preparation for studies overseas (I need a master's degree to be able to apply a master's degree overseas). I am wondering of possible thesis topics acceptable for a master's degree. The school I am currently in has a few...
  6. Sakurasus

    Engineering Electrical engineer & physicist, advice on PhD astronomy

    Hello everyone, I have read a lot of the post here about being engineers and going on into astronomy or astrophysics. Thus, decided to join and ask for advice. I have a similar experience but I have a unique problem. I have an BSc in electrical engineering from a US university with focus on...
  7. WineRedPsy

    Cosmology or Theoretical Physics?

    I don't really have to look into this just yet but it bothers me. I quite like cosmology and stuff like such. Universal topology and relativity and sum of histories and stuff. Fun! I really would like to study any theoretical physics though, it just strikes my fancy particularly. I figure I'd...
  8. C

    What are the alternative career options in astrophysics besides research?

    Hello everyone! I'm a junior at the University of Michigan, currently on a path to double major in Physics and Astronomy, which would be followed by grad school for a Ph.D. in astrophysics (if all goes well). My entire life I thought I wanted to be an astrophysicist, but I'm beginning to become...
  9. Mare Vaporum

    Hi, I'm a little late with my Introduction.

    Some of you may have seen me before, but I ridiculously forgot to post my New member introduction, my apologies. I love science, especially astronomy, and I am glad to be here.
  10. juliact15

    Which courses should I take for a concentration in Astronomy?

    I am an undergraduate Physics major in my third year, and I'd like to concentrate in Astronomy or Astrophysics when I obtain my Masters and PhD. What kinds of physics classes should I take in preparation for this? I've already taken all explicitly-astronomy courses at my school. I was thinking...
  11. A

    Moon Phases: Rise & Set Timings & Direction Explained

    Hello! Why does the moon has different rise and set timing for different phases? And also, why does it rise from different directions during different phases? Help me out please!
  12. S

    I require help with understanding beginner astronomy questions.

    First, I'd like to make clear that this isn't exactly homework. I've been reading books about astronomy out of pure interest and I've bought myself an introductory astronomy textbook and I've been reading through it and answering all the questions. I've been doing fine... that is until I reached...
  13. E

    Where did all the physics ladies go?

    First of all, I'd like to clarify my title by pointing out it is NOT a dodgy pick-up line. I am a female myself and have noticed that pretty much every woman who enrolled at my university in physics is going on, or plans to go into the field of astrophysics, myself included. I am wondering if...
  14. P

    Astronomy iron ratios in galaxy

    Homework Statement I understand that [Fe/H] ratios can be used to describe metallicity in a galaxy... but I'm having trouble understanding what [element/Fe] ratios should tell you. Anyone have an idea? Homework EquationsThe Attempt at a Solution
  15. M

    Engineering Advice for a Late Bloomer in Math and Science Majors

    So I need a bit of outside input. I am 20 years old, enrolled in my second year of community college (going for 3 years because I ended up starting late and going less than full time my first year). I did terribly in academics in high school, especially in math and science classes. Well, long...
  16. M

    Engineering Space Companies/Agencies that hire astronomers, physicists & aerospace engineers

    I'm only a freshman in college, but I am always thinking about the future. I plan to earn my Bachelor's in Physics or Astrophysics, and then continue onto graduate school. I'm at Penn State University, so I plan to stay here for all of my degrees unless a better, more valuable opportunity...
  17. A

    Astronomy: Find Star Rotation Period with Given Data

    Homework Statement Find period of the star's rotation assuming that the axis of rotation is perpendicular to the direction of view. Given data: - distance d = 25 pc - bolometric luminosity observed m = 8m - effective temperature T = 4000 K - bolometric absolute brightness of the Sun Mm = 4,75m...
  18. moriheru

    Introdutions to mathematical astronomy?

    Does anybody know of a good Introduction to the mathematics of astronomy or astrophysics?
  19. I

    The Nature of Time: Physicist's Interpretations & Thought Experiments

    I am interested in how physicists view time, and in any thought experiment (eg. anti-matters time direction, spinning black holes that may have the time dimension no longer orthogonal to the three special directions, delayed quantum eraser experiment that might permit backwards in time...
  20. benlahbib

    The fabric of the cosmos - Universe or Multiverse

    "The Fabric Of The Cosmos," a four-hour series based on the book by renowned physicist and author Brian Greene, takes us to the frontiers of physics to see how scientists are piecing together the most complete picture yet of space, time, and the universe. With each step, audiences will discover...
  21. A

    Engineering Little concern about choosing the practical major between astronomy and engineering

    I'm a grade 11 high school student who has passion for his dream of being an astronaut someday. My classes are mostly science related because I thought I needed them when I get to choose my major. I'm planning on going to university of toronto after I graduate, I was thinking of majoring...
  22. P

    Who Determined the Phase and Period of Epicycles in Greek Astronomy?

    I've researched multiple histories of Greek astronomy, and have not found a satisfactory answer to this. When describing multiple deferents, each with a first order epicycle, many illustrations show the epicycles at different phases of their rotations: Mars will be at 37 degrees, Jupiter at 123...
  23. R

    Doppler Shift and Astronomy

    Homework Statement The Sun rotates with a period of 24.7 days and has a radius of 7.00 x 108 m. For a terrestrial observer, Calculate the resultant Doppler shift of light of wavelength 500 nm which is emitted from the solar equator at : i)each side of the disc, ii)the center of the solar disc...
  24. L

    Is There a Simple Equation for Hubble's Constant and Time in Astronomy?

    I found an equation relating hubbles constant and time!It is highly simplified but helpful! http://www.astronomycafe.net/qadir/q679.html da/at = (2/3)*a0* (1/t0) * (t/t0)^-1/3 then dividing by a = a0 (t/t0)^2/3 you get H(t) = H0*(t0/t)
  25. M

    Astronomy; Precession data co-ordinate systems

    Homework Statement Use a coordinate conversion application to roughly map out the amount of precession in coordinate positions (R.A and Declination) in the sky between 1950 and 2000. Homework Equations I can easily find a converter on the internet The Attempt at a Solution I...
  26. F

    Graduate Programs for Radio Astronomy

    Hello all, I'm trying to compile a list of schools (mainly in the US) that offer Ph.D. programs with research in radio astronomy. Here's what I've come up with so far: Caltech Cornell Harvard New Mexico Tech Ohio State University UC Berkley UC Los Angeles UC Santa Cruz University of Arizona...
  27. C

    What Are Some Recommended Astronomy Books for Laypersons?

    I'd like to read some layperson level materials about astronomy and astrophysics, what do you recommend?
  28. Greg Bernhardt

    Astronomy Calendar of Celestial Events

    Sea and Sky does this the best. Here are the expect events for the next several years. Feel free to post a new thread for one you are interested in discussing. http://www.seasky.org/astronomy/astronomy-calendar-current.html
  29. T

    I need someone good at astronomy

    I'm not a very scientifically or mathematically advanced person, so try not to bash me for this question, but I needed to know the answer for a certain debate I'm having. If a planet or 1 km in diameter had 10 times the gravity of Earth, what would be its mass and/or density? P.S...
  30. S

    Astronomy Day is coming at my university; any suggestions for demos?

    Thank you for anything you can offer. We've got a plasma globe which we can tie into talking about solar and interstellar plasma, and we have a few Galileoscopes, but we don't really have anything else astronomy-themed. I've been thinking, but haven't come up with many ideas. One idea I did...
  31. V

    Astronomy: Explaining Why Stars on Top Left of Main Sequence Spend Less Time

    Hi, I was just wondering if anyone could help me with this question. I couldn't find anything on the internet. Q12 Explain why a star on the top left of the main sequence will spend much less time on the main sequence than another star on the lower right
  32. Y

    Programs Double Major Astronomy & Biophysics

    I think I have finally decided I want to double major in Astronomy and Biophysics. There seems to be great overlap because most of it is just physics. I am a sophomore at UT Austin. Do you think this is a wise choice. I kind of just want to follow my interests rather than worry about future job...
  33. S

    Astronomy vs Aerospace: Career Choice Help

    Hi I was wondering which would be a better career choice. I have been in love with space my entire life and I never want to give that passion up. I am about to start applying to college and I don't know if I want to be an aerospace engineer or an astronomer. My hope is that if I become an...
  34. B

    I'm interested in switching careers to the astronomy field(s)

    Hi everybody! I've recently decided to make a substantive change in my life, and leave the legal profession for the astronomy world. I am not all too keen on accruing debt or working in a legal capacity. But I 'm figuring that there must be a decent-sized body of support personnel...
  35. U

    Pursuing Astronomy Career: Physics or PhD?

    I have been considering astronomy as a career choice. I read on yahoo answers that a PhD is the one way to go in terms of this option. There isn't much career options for just the BA. Also, it was recommended that I obtain my BA in physics for my PhD in astro, as I would be robbed of...
  36. George Jones

    News John Dobson: Pioneer of Amateur Astronomy

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  37. T

    Programs Astronomy or Astrophysics degree and research.

    Hello fellow members of this forum, I am highly interested in Astronomy and Physics, and I plan to pursue a career in these fields. I am debating on whether I should try to study towards earning a B.Sc in Astrophysics or Physics when I graduate from high school in 2016 (then continue it...
  38. A

    Exploring Pulsars: Age, Pulse Height, and Distance through Radio Astronomy

    Hey guys, I'm in the middle of writing a lab report and I'm having trouble with my abstract. I know as a 3rd year uni student I should know how to write one by now. I feel it's a bit long, what do you think? How could I improve? I'm not asking you to write it for me just some hints. The...
  39. P

    Astronomy: abundance, concentration, density

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  40. A

    Astronomy homework question - stars emitting in infrared

    Astronomy homework question -- stars emitting in infrared Dear All, Hello! This is my first post. I am taking a distribution introductory astronomy course (low on math) and am having trouble with this question: Which object emits more intense infrared radiation: _ the Earth _ the Sun...
  41. L

    Programming jobs related to astronomy

    I am currently a math major and I have one more year before graduating with a bachelors degree. There aren't many career opportunities for a math major -- with only a bachelors degree -- other than being a teacher or going to graduate school; which I heard is very challenging and has a lot of...
  42. S

    Engineering Can a degree in physics or astronomy lead to a career in aerospace engineering?

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  43. Spinnor

    Feynman's New Zealand lecture, Inca astronomy, rule and reason.

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  44. J

    Astronomy book listing Ceres as a planet?

    Does anyone know of a (relatively) cheap astronomy book which has Ceres officially labelled as a planet? I realize it may not be extremely cheap seeing that it would have to be from the 1800s, but perhaps there's one that was commonly enough in print to not be so hard to find? It's both...
  45. K

    Positional Astronomy: Zenith, celestial poles and sidereal time

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  46. C

    Amateur Astronomy - Learn What to Look For in the Sky

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  47. J

    Stellar or Solar system Astronomy?

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  48. S

    Which universities in Australia offer a PhD in Astronomy?

    Hi I am a Physics masters student from India in a college in Texas. I want to pursue a PhD in Astronomy (observational/radio) Australia. I have heard Australia is very good at obs astronomy - however google searches are revealing a lot about the telescopes and other facilities there but...
  49. S

    What universities in Australia offer a PhD in Astronomy?

    Hi I am a Physics masters student from India in a college in Texas. I want to pursue a PhD in Astronomy (observational/radio) Australia. I have heard Australia is very good at obs astronomy - however google searches are revealing a lot about the telescopes and other facilities there...
  50. astroscout

    What is the connection between hurricanes, spiral galaxies, and sunflowers?

    Nature,Astronomy and Physics have facinated me for years but I had no idea they were eerily similar in other ways. Nature produces hurricanes that in satellite photos look eerily similar to those of spiral galaxies photographed by the Hubble space telescope. Physics uses a model...
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