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. DHF

    Need help with astronomy details in a book.

    Hi and thanks in advance for any help. The book I am currently working on features a protagonist that is an astronomer, I was hoping those more knowledgeable then I could check the passage where she describes her work and make sure it doesn't sound like gibberish. much appreciated. "Though she...
  2. Prins

    Astronomy Books on Astrophysics and astronomy

    Hi I have done my m.Sc now I'm interested in the field of astronomy but there were no subjects regardind astronomy in my masters course work I'm thinking of going into a PhD So I wanted to check aa the topics and get myself to the level to do PhD so please suggest some books
  3. CrackerMcGinger

    Need reliable resources on basic astronomy and quantum physics

    I've been relying on Wikipedia and some other questionable sources for a basic understanding of these studies, and i don't think I should rely fully on these sources. If anyone can point me to a place that is reliable I would greatly appreciate it.
  4. S

    Best Country for studying Astronomy

    Which country is best to study astronomy? To be specific which university is preferred.?
  5. S

    Career related to Astrophysics and Astronomy or other space

    So what I want to ask is that I will be entering a university next year so career selection is one of the very tricky and difficult decisions. MY question is that what if I do Some PhD in astrophysics or astronomy what type of job can I get other then a professor.? And as an foreign I may not...
  6. A

    I Is there any international astronomy competitions for adults

    Hello every one . I am 19 years old and i can't be in olampiyad of astronomy . actully i really want to be in a international astronomy competition but i don't know whaaat ?? please help me . thanks
  7. sunrah

    Yay, starting my Astronomy MSc this month

    After all those years of doing physics, I finally get to do something that interests me :woot: Just kidding, good luck to everyone starting at uni this year!
  8. F

    Calculate flux from a radiating disk

    Homework Statement Suppose you have a disk of radius r at x=y=z=0 with its normal pointing up along the z-axis. The disk radiates with specific intensity I(\theta) from its upper surface. Imagine the observer plane is at z=Z, where Z is much greater than r. Let I(\theta) = I = constant...
  9. Armando Valle

    Hey everyone, where can i study astronomy on internet?

    hello everyone, can someone help me know where I can take a course in astronomy / cosmology on the Internet where you get recognition and diploma and to get on with my passion of the universe? This means a lot to me and I want to move on in my passion. thanks
  10. Armando Valle

    How do we know galaxies are exactly where we see them?

    i have a doubt, how do we know far away (light years) galaxies and planets are on the right spot we see them? if light takes a lot of time to reach the Earth it means we are seeing the past of the galaxy/planet. Example: If Earth is becoming extinct and we need to find an exoplanet 30,000 light...
  11. B

    Teaching Astronomy to 11-16yr Old Boy Scouts

    I'm an 18 year old scouts member; which makes me one of the "elders" of the boy scouts. My chief has asked me to prepare an astronomy session to teach to 11-16 year old boy scouts. I'll be joining them on their summer camp in 2 weeks time. So I'm supposed to wake them up in the middle of the...
  12. C

    Astronomy Good ancient to modern history astronomy books?

    Hi, Can anyone recommend some good ancient astronomy books (from around 8000BC-0) that that are historically correct (perhaps springled with a few translations from older writings) with visual images, and that show in some detail how different calculations, and observations were made? It would...
  13. Quotidian

    Earth-Like Planet orbits Sun-Like Star

    That, anyway, is the headline in today's news, regarding the interesting discovery announced by NASA overnight of the planet dubbed Kepler-452b. As I understand it, the properties of the planet are inferred from spectral analysis of its effects on the light from the star which it orbits...
  14. Ibrahim Hany

    Ideas for Camp activities/workshops

    I am not sure if this should be here or in Astronomy forum! I am participating for my second time in an astronomy camp for children from 8 to 16 years as a teacher. Last year I designed and prepared three workshops; one on Stargazing, one on telescopes, one on rockets. The only fault that I...
  15. N

    Jobs to gain useful experience in astronomy/astrophysics

    Hey guys & gals, a long time lurker here. For a variety of reasons I have failed to secure a PhD position that I wanted this year after finishing my MPhys degree in physics, so I decided to take a year away from studying, regroup, work towards publishing a paper and then come back with full...
  16. P

    Should I take an extra year as an undergade student?

    Hello, I'm currently a philosophy major and I'm going to start my sophomore year this fall, but I've considered changing my major to astronomy. The problem with this is that I've always wanted to graduate in just 4 years, and the only way this could happen is if I filled up the next two summers...
  17. BruceW~

    Books for High School Science: Astronomy, Chemistry, Biology, Calculus

    Hi guys I'm Bruce. I'm new to this forum and I 'm currently a high school student. I was wondering if there was any good books( not too advanced) on topics such as astronomy, chemistry, biology and calculus. If you can give me one or two suggestions that will be great.
  18. I

    Masters in Physics and Astronomy with a BA in English

    I am a career switcher who is extremely interested in getting a masters astrophysics. I have an undergraduate in English with very few science credits (I took 8 units of geology). I am currently enrolled in community college taking as many science and physics classes as I can. Does anyone know...
  19. Y

    What is the procedure to study astronomy if i have done B.E?

    PLEASE HELP I HAVE COMPLETED BACHELOR IN ELECTRICAL ENGG. AND I HAVE INTEREST IN ASTRONOMY SO, WHAT IS THE PROCEDURE TO STUDY ASTRONOMY IN INDIA AS WELL AS IN ABROAD?
  20. D

    Books for Beginners (Astronomy & Astrophysics)

    In the next month, I'll study about Astronomy and AStrophysics, so what are the good books for me ? Please ! I really love Astronomy !
  21. Y

    Recently i have pursued B.E. in electrical eng. .

    what I should do if i want to study astronomy now?
  22. K

    What Does the Observable Universe Look Like?

    The entire observable universe is contained rather graciously in this wonderful picture, for your admiration.
  23. P

    Exploring Nature: Joining Discussions on Software Testing and Astronomy

    I am looking forward to joining discussions here. My Backgroud is 2 years "applied physics", 5 years education for teaching in visual communication (art), 15 years experience as a database software developer. Now I am looking for a job as a software tester. Software Testing is similar to being...
  24. D

    How to Pursue a Career in Astronomy - Realistic Advice

    Is this realistic or really just a fantasy career that almost no one ends up doing? I would love to learn about space and the universe, but just feel those jobs a extremely rare. Can anyone give me any realistic advice on how to getting a job as an astronomer? Thank you all!
  25. N

    How do galaxies die? Contradictions between two papers

    Hi all! My name is Nova and I have recently started a research project on the life cycle of planets, stars, galaxies, etc. I posted this question on reddit, but no one seemed particularly interested. Someone suggested I consult the ultimate physics community on the web, Physics Forums, so here I...
  26. N

    How do galaxies die? Contradictions between two papers.

    Hi all! My name is Nova and I have recently started a research project on the life cycle of planets, stars, galaxies, etc. I posted this question on reddit, but no one seemed particularly interested. Someone suggested I consult the ultimate physics community on the web, Physics Forums, so here I...
  27. S

    Practical or sell-able skills of astronomy graduates

    Just being very curious, what do graduates of Cosmology, Astrophysics, or Astronomy do for careers? Do some or many employers wonder if these graduates have practical or sell-able skills? These people must have had other courses and have dealt with technical, equipment, engineering skills...
  28. B

    Exploring Light and Physics: A Scientist's Journey of Discovery and Learning

    Hi. 4 years ago my child asked to me a question... What will be happen, if the light is stop? I tried to answer it ... But my knowledge is insufficient. (I had been educated at social science, specially labor laws) . So I searched, tried to learn something new... So I liked physics. Of course it...
  29. AgentSmith

    Astrophysics Unlock the Math behind Astronomy: A Student's Guide by Fleisch & Kregnow

    Student's Guide to the Mathematics of Astronomy, by Fleisch and Kregnow. For beginners, uses algebra, geometry, and trig applied to astronomy and cosmology. Helpful for students who get bogged down in mathematical manipulations and coming up with equations in the first place.
  30. R

    Proof that the moon is closer to Earth than the sun

    How can I prove to my 9 year old daughter that the moon is closer to Earth than the sun? At the moment, she has read it in books and this information has the same status as unicorns and fairy princesses!
  31. M

    Studying Astronomy: Struggling with Cosmology Maths

    Hi everyone. Loving the forum, don't know how I haven't stmble upon it already. I'm studying Astronomy at the OU and finding a lot of the maths tough. Especially finding the chapters on Cosmology very difficult. I've seen another post regarding Scale Factor, so hope it's ok posting this too...
  32. Greg Bernhardt

    Astronomy and Cosmology FAQ List

    PF Insights Blog https://www.physicsforums.com/insights/postindex/ Was the early universe in a disordered state? Why is the radius of the observable universe in light-years greater than its age? Where did the Big Bang happen? Would that be the center of the universe? What is the total...
  33. acdurbin953

    Astronomy derivation, leading to question about oscillations

    Homework Statement The sun experiences a vertical gravitation acceleration of g=-4πGρz, where ρ is the density of the disk of our Galaxy. a) Assuming that d2z/dt2=-kz, express k in terms of ρ and G. b) Find the general expression for z and w=dz/dt as a function of time. c) If the total mass...
  34. Hunter Brandon

    Time Theory in Astrophysics: How Is It Possible?

    I'm new to Astrophysics but some scientists say that all time is happening at one time. How is this possible if the universe is still expanding
  35. R

    Astronomy: Speed at the edge of the galaxy

    Homework Statement The number of stars in the galaxy is N=10^12 and the radius of the galaxy is Rgalaxy = 20 kPc Let m be the average mass of a star in the galaxy. what is the velocity of a star at the edge of the galaxy (relative to the center of the galaxy) Homework Equations The Attempt at...
  36. F

    Astronomy: Sun azimuth from altitude, hour angle, and declination

    Homework Statement Hi everybody, I am trying to do a numerical aplication of change of coordinate system to another; the objective is to calculate the azimut of the sun knowing the altitude, hour angle and declination . Homework Equations Cosh * Sina = Cosδ * Sin H where a is the azimut h is...
  37. Y

    What is the difference between astronomy study and astrophysics study ?

    Which one let's you to have your own lab and make mind-blowing experiments without any interuption for you to think and create something new and to explore something profound ? ( I know there is something wrong but i'd like to learn)
  38. S

    Understanding Big R(t) in Astronomy: A Physical Perspective

    I'm having trouble with with understanding what this is, our text, Astronomy: a physical Perspective by Kutner, uses R(t). I understand r(t) is the distance between two objects at a point in time, but what is the scale factor big R(t)?
  39. L

    British Olympiad in Astronomy and Astrophysics Competition

    So I've been told recently, that I will be participating in the "British Olympiad in Astronomy and Astrophysics Competition", which I am really excited about. I took the British Physics Olympiad Paper earlier this year, and feel like I could've done better.So because I am quite new to Astronomy...
  40. 2

    Can white dwarfs have iron cores?

    Wikipedia only talks about helium and carbon-oxygen white dwarfs... I understand that on a red giant you only get fusion up to oxygen, but I though that maybe if you had a red supergiant which produced iron in its core, and when it exploded as a supernova it threw off enough mass to form a white...
  41. 2

    Stargazing Understanding reflecting telescopes?

    I have been looking at these diagrams: From the following link http://www.astronomynotes.com/telescop/s3.htm And I just can't seem to figure out why the first telescope design doesn't show a shadow and in the second why the presence of the secondary mirror, and the hole, do not affect the...
  42. 2

    Question about spectral lines of stars?

    I can't seem to find an answer to this quick question: which part of the star causes the observed spectral lines? As I understand, the photosphere is the deepest visible layer of the star, and then light passes through the chromosphere and the corona. I would think that both the chromosphere and...
  43. 2

    Stargazing Quick question about telescope classification

    I am slightly confused about what the term 'astronomical telescope' covers. My textbook seems to be implying that astronomical telescopes are refracting telescopes with an objective and eyepiece lens, and reflecting telescopes are separate to astronomical telescopes. On the other hand I have...
  44. 2

    Stargazing Viewing stars through a refracting telescope?

    Hello! I am learning about refracting telescopes and am slightly confused. I have read that a refracting telescope will magnify planets, but not change their brightness, but will not magnify stars as these will remain as point objects. It just makes the stars appear brighter. I am slightly...
  45. GiantSheeps

    Stargazing Are there astronomy competitions?

    I run an astronomy club at my school, and I recently discovered that the robotics club gets $2000 from the school every year to build a robot. They then go on to compete in tournaments with that robot, so that justifies the $2000. It would be great if I could get the school to give us $2000 to...
  46. S

    Bisque Software for Astronomy SkyX

    I'm taking a shot that this forum might know about the software in the title, SkyX. My question is about a feature called Profile. I need some help using it.
  47. L

    Calculating relative velocity of Crab Nebula

    I'm using the the Doppler formula to calculate the relative velocity between the approaching and receding filaments of the crab nebula: Δλ/λnaught = v/c Change in wavelength/ wavelength = velocity/ speed of light I have reworked the formula as v= c(Δλ/λnaught) When I plug in the values I get...
  48. A

    What electives would be most beneficial?

    I recently changed my major to physics from business. I would be going into my senior year as a business student had I stayed, so I have all my core requirements done. While I'm catching up on some maths, I'll need to fill my schedule with electives to remain a full-time student. What courses...
  49. B

    Found out I received an offer to the Harvard SAO Astronomy REU

    Hello, Tonight, I received an email from the Harvard faculty that they wish to call me regarding their REU. I was incredibly excited, but I do not know what questions to ask. I am in total shock as I thought I would never believed I would have received an offer from Harvard of all places. What...
  50. akshaya

    What Lies Between Universes and the Big Bang? Exploring the Multiverse Theory

    Well, the string theory talks about multiverse, unlike the Big Bang theory. Michio Kaku explains it by comparing it with bubbles. There are many universes. These universes are like bubbles floating around, and when they collide, they form a single bubble- a universe. When a single bubble...
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