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. M

    Engineers in the field of Astronomy and Astrophysics

    I have had a love for astronomy when I was a child. Today, I am well on my way toward becoming an engineer (Mech). I would like to find out how much of a common thing is it for engineers to go work for astronomical societies/research institutes/ observatories doing any kind of engineering...
  2. H

    Astronomy Olympiad Estimation Question

    Homework Statement Q. Given that the population of Mumbai is about 13,000,000. Estimate the amount of tea that would be consumed by the city in a day? 2. The attempt at a solution Now at first place I could not understand why such kind of a question is given in Astronomy Olympiad...
  3. Z

    Calculating Sidereal Time for a Star's Upper Culmination at a Given Location

    1. Homework Statement It's a very simple (I guess) astronomy problem but I have no idea how to start and what to do, so please show me something. One star Σ has (right ascension) α=1h25m18s. What is the (sidereal time) ST at Thessaloniki (φ=40.5°, λ=-23°) when the star is at its upper...
  4. M

    Programs Physics and astronomy major should I drop the astronomy? Help please

    Hi everyone. I'm currently in the second semester of my second year, doing a combined degree in physics and astronomy. I really love physics, and have no doubt I will continue in that direction. However, I've always been interested in astronomy outside of school... So it seemed like the...
  5. E

    Difference between astronomy and cosmology

    well, dear all first i want to introduce myself, i am a mechanical engineer working professionally as a piping stress analyst in a multi-national firm, well cosmology and the things abt the origin of time and space etc seems to be very nice things to study and i am new to them, can u please tell...
  6. B

    Stargazing Telescope and astronomy questions

    My friend has a telescope that I think is controlled with a motor. Does this kind of telescope have to be hooked up to a computer or something. Were going out to look at Mars and I don't really know anything about setting up telescopes or anything. What kind of computer program would I need...
  7. G

    Programs Engineering and Astronomy: Double Majoring the Universe

    Can you double major in Engineering as well as Astronomy/Astrophysics
  8. M

    Fiction Writer Looking for Some Astronomy Help

    Hi There, I'm a novelist working on a science fiction adventure, and I could use a little help on the astronomy side. I'm not looking to get down to the inner workings of quantum formulas, but I do want to make sure that I'm at least being reasonably on point given the fact that I can fudge...
  9. M

    Fiction Writer Looking for More Astronomy Help

    Hey Physics Gang, I'm onto my next writing phase and would appreciate any help you can give me on this round of questions. Here we go (Many of these questions will relate to Space Shuttle launches): As is, the Space Shuttle essentially hitches a ride on a rocket, which handles the launch...
  10. O

    Beginners Questions about Astronomy

    Hello, I have a few questions for astronomers. 1) When you look up at the sky at night with the naked eye, are all those stars within the milkyway galaxy? Or can we see past our own galaxy and see stars from other galaxies mixed in with stars from the milky way? 2) I heard the universe...
  11. E

    Get Astronomy Homework Help for Confusing Problems - Due Tomorrow Morning!

    http://www.physics.utah.edu/~cassiday/p1050/homework05.html I am a procrastinator- this assignment is due tomorrow morning, I need some help. I am really confused with 7 and 8 and that's how far I am. Any help or tips are appreciated!
  12. M

    Fiction Writer Looking for Astronomy Help

    Hi There, I am working on my second novel, a kind of Buck Rogers-type adventure, and I want to make sure that I'm being at least reasonbly accurate in regard to what an "outer space" journey might be like. It's going to be light in tone and I'm not looking to get into lots of particle talk...
  13. B

    Barycentric Julian Date (astronomy)

    Homework Statement I'm wanting to convert barycentric julian date to the equivalent UT time. Here is a description of the barycentric julian date given to us: Barycentric Julian Date (TT) – Observation epoch, given in terrestrial time, that has been corrected for light propagation time to...
  14. S

    Start Astronomy & Physics: High School Student's Guide

    I am a high school student right now (11th grade) and I am really interested in studying Astronomy and Physics. I asked my Astrophysics teacher if NASA has Astronomy jobs, and I believe he said that it would lean more into Physics or "Astrophysics" And he said that they look for people with...
  15. P

    Need homework help (Astronomy)

    I cannot figure out the answers for the following problems: 1) If a star has a parrallax of 0.016 second of arc and an apparent magnitude of 6, how far away is it, and what is its absolute magnitude? 7) If a star is 10 times the radius of the sun and half as hot, what will its luminosity be...
  16. J

    Calculating Black Particle Size in a Red Giant Solar System - Astronomy Homework

    Homework Statement When the Sun becomes a red giant star its brightness will increase by a factor of 5000 and its mass will decrease to half of its present mass. When this happens particles smaller than a critical size will be blown out (light force = gravity force) of the solar system by the...
  17. P

    Astronomy - Latitude and Longitude problem

    Homework Statement An airliner flies from London Heathrow (latitude 51^{o}30' N, longitude 0^{o} 10' W) to Tokyo Narita (latitude 35^{o} 40' N, longitude 139^{o} 45' E). Assuming that the Earth is spherical and the aeroplane takes a great circle route, a)what is the total distance flown...
  18. J

    Astronomy Question: Est. Sun's Power & Temp

    [SOLVED] Astronomy Question Homework Statement This is a two part question. I believe the problem I'm running into is coming from the answer to the first question. Q1: Hold your hand 7.5 cm from a 100 watt light bulb and you will feel the same heat sensation that you feel when your hand is...
  19. K

    How can I apply Wien's and Stefan's laws to solve these astronomy questions?

    I am having a hard time with these astronomy questions. Our teacher gives us no help and I am lost with this stuff. If anybody could help me out not just with the answer but on How to do it I would be most appreciative. What would be the frequency of an electromagnetic wave having a...
  20. L

    A question for hams/radio heads: radio astronomy

    I am looking at a cheap $100 shortwave radio, the Kaito KA-2100 (google it, there are a bunch of links, too many to mention), and I would like to know if disabling the AGC (automatic gain control), is possible for use as a radio telescope. Now I don't know that much about radio and electronics...
  21. A

    Astronomy & Astrophysics 210 - and misc questions

    Hello there, I was searching the net to find some empirical formulas on how to estimate the loss in temperature (and increase in luminosity of a star as it ends the main sequence. I've found that some of these formulas could be located in a book called "Astronomy & Astrophysics 210" by Maeder...
  22. Lisa!

    Searching for a Dream Article: Astronomy Meets Metaphor

    A few days ago I guess I got to a new article regarded to astronomy in Yahoo! I don't remember exactly what was the title since I just had a glance at that and didn't have enough time to read it but it seemed to me there was something like "planets splash the satrs(eh?) like flies splash...
  23. B

    Why Does My Normalized Star Flux Data Show a Bimodal Distribution?

    Homework Statement I'm absolutely desperate for help on this. The image supplied below is an image of a frequency histogram for the V-band Tycho photometry data (from the Tycho Epoch Photometry Annex). What I've done is this: 1. I've converted the V-band magnitudes into flux so that it is...
  24. B

    Statistical analysis of photometric data - Astronomy

    Homework Statement My class is doing an assignment where we have to create a programme to convert the Hipparcos data from magnitudes to flux so that it when you plot a frequency histogram of the data you will have an approximation of a normal distribution. I've completed this OK, but I was...
  25. ZapperZ

    Is Too Much Physics Bad For Astronomy?

    I didn't realize there was such "animosity". http://www.nature.com/nature/journal/v447/n7141/full/447122a.html" in this week's edition of Nature (the link is open without subscription only for a short time). So, for people who are majoring or working in this field, do you share White's...
  26. F

    Exploring Astronomy: Dead Stars and Solar Systems

    I have a question about dead stars. I have only read about 2 ways a star can die. Either explode into a supernova or collapse into a black hole. It seems strange to me that when a star consumes all its energy that it could not simply become a huge lump of slag out there. Is it possible that...
  27. murshid_islam

    Exploring Astronomy, Astrophysics & Cosmology: Unpacking Alan Guth's Quote

    i have 2 questions: 1. what is the difference between astronomy, astrophysics and cosmology? 2. what did Alan Guth mean when he said, "The universe is the ultimate free lunch"?
  28. B

    Radio Astronomy - power received

    Homework Statement Compare this to the power received on the ground from a geostationary satellite with a 1 W transmitter and with a transmission footprint of 1000 square km across (assume uniform power in footprint). The Attempt at a Solution I don't know where to start on this one...
  29. S

    Astronomy spectroscopic binary

    i have been trying to do this problem for an hour and i have no clue what to do for it... please help me It's on the 4th page down and it is called "Spectroscopic eclipsing Binary System" htt p://www.tufts.edu/as/wright_center/fellows/sci_olympiad/Spok_2000_C_Instrcs_&_Quests.pdf...
  30. B

    Access to astronomy journal articles

    Hey guys, Do any of you know a free database with a wide variety of journal articles that I can search? I want the full text articles, but most databases search abstracts and then give you a link to a site where you have to pay for the full text version. I mean I am told of these...
  31. M

    I'm Living in the Astronomy Section

    Having seen the horrors of long times between posts, and the starving databanks ready for more information, I am officially moving to the astronomy section. My experience may be questioned, but I can assure you that I do know a lot about Space in general, even though my AstroPhysics is...
  32. S

    I need some serious help here soon Astronomy Binary stars

    This problem deals with two main sequence stars in an eclipsing binary star system. I need to determine the system's peiod and separation (P and a). Right now i know that the brightest star has an absolute magnitude of -1 (219 solar luminosity), is 17,000 degrees kelvin, has a radius of...
  33. R

    Astronomy Olympiad: Questions & Discussion

    Recently I gave my Astronomy Olympiad. There were some questions of descriptive type. If you all don't mind I would like to discuss them here. :rolleyes:
  34. F

    Astronomy and the Relativistic Doppler Shift

    Homework Statement The hydrogen atoms in a star are also moving at high velocity because of the random motions caused by their high temperature. As a result, each atom is Doppler shifted a little bit differently, leading to a finite width of each spectral line, such as the 656.46-nm line we...
  35. N

    Astronomy Help with Spectrography

    Homework Statement I posted a similar question before but I am just having some difficulty understanding the relevance of one of things mentioned in this question and I'm wondering if anyone here can help clarify it. The problem is what is the relevance of the star spinning at a velocity of...
  36. F

    Astronomy Song Game - Get Creative!

    Alright, basically you have to think of a song that in some way relates to a planet, star, moon, astronomer, concept, theory, astronomical term, etc. Expect some to be funny. I'll start off: I still haven't found what I'm looking for - U2 - Dark matter/energy Here comes the Sun - The Beatles...
  37. N

    Astronomy Spectroscopy help

    Hello all, I am currently doing a 3rd year Astronomy and Astrophysics course and I am having some trouble with the current problem set (this is mainly because our teacher doesn't really teach us anything but that's another story). This is the question in particular that is bothering me...
  38. C

    Astronomy related angle question (more of a Trig Q)

    For an astronomy lab I am looking at pictures of the moon, measuring pixel distances and converting to km. Easy enough for the diameter of a crater, but the depth gets more complicated. To find the wall height of the crater, you measure the shadow length and the angle of altitude (theta in...
  39. O

    Astronomy - aphelion/perihelion from conservation

    Hi all, I'm stuck on this question for my assginment...i need to derive the velocity at perhelion and aphelion using two separate methods: the conservation of specific angular momentum and energy. I think I'm OK with the energy part but I'm stuck on getting the velocities at aphelion and...
  40. R

    How Would Changes in the Sun's Mass and Earth's Velocity Affect Earth's Orbit?

    Q.1 If the mass of the sun is reduced by 1% and the Earth's velocity is also reduced by 1%, what will be the trajectory of the earth?
  41. U

    Astronomy Question: Differences Between Nebula and Death Star

    I want to know what is different between nebula and a death star?
  42. H

    MSc Astronomy @ SAO: Pre-Requisite for PhD in US?

    I am planning to puruse the Distance Education Astronomy course (MSc in Astronomy) offered by Swinburne University of Australia (SAO). I already have a Master's degree in Chemistry (post graduate thesis being part of this) and a Bachelor's degree in Electronics from a reputed Indian University...
  43. F

    Saturn's Rings Backlit: Glorious Detail & Light

    Saturn's rings backlit. You can see ALL the rings in glorious detail and light. It's beautiful. http://www.badastronomy.com/pix/bablog/2006/saturn_backlit_glow ...Any other amazing pictures?
  44. P

    Solving Sun-related Astronomy Questions: Wattage and Fusion Calculations

    I'm taking Astr. 321 right now. We were supposed to read the first 3 chapters. They go through the different planets (some detail, but nothing too complicated), the sun, asteroids, etc. The lectures went over this in more detail and went through things like which elements were created first...
  45. Q

    Astronomy in West LA: Can You Observe with a Telescope?

    Question: I live in west Los Angeles, and I was wondering if I would be able to see much at all with a personal telescope, if I got one. I imagine the light pollution would prevent me from observing anything but the brightest of objects (Moon, Venus, Polaris, etc). Has anyone attempting to do...
  46. S

    Is It Too Late to Pursue an Astronomy Career at 37?

    Hi all, Does anyone knows of any Astronomy graduate who earn Phd or Bsc or Msc at age between 35-45? Whats the oldest age ever to get Astro Phd? I have a Bachelor of Science in Physics ( Boston , MA) and I am 37 years of age, I have applied ( sucessful application) to do Master ( One...
  47. V

    The Astronomy Peer Review Process

    SpaceTiger's Note: Taken from https://www.physicsforums.com/showthread.php?t=130680" Sorry, this question is somewhat off-topic, but aren't the arxiv.org-papers peer-reviewed?
  48. S

    Probability in an astronomy career.

    I am a 22 yr old girl. I just went back to college and I am double majoring in aeronautical engineering and astronomy. I am little confused as how to strt getting internships and such in my field. Also, I don't really know how to go about having a career in astronomy. I do realize that i'll be...
  49. A

    Travel & Astronomy: Exploring the Benefits of Combining the Two

    Is traveling a big deal when your an astronomer?
  50. cepheid

    Topics Applicable to Astronomy

    Hello, I'm in the midst of choosing technical electives (in the Engineering Physics program). I am just wondering what sorts of Electrical Engineering topics might be applicable to astrophysics, or space science in general? I hope this question is not too vague, but I have a choice of...
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