beanie001 wait, but isn't astronomy and astrology basically the same thing? humans always seem to talk about both with the same credibility.

space101 what even are you? a green alien drinking cola? okay, anyways, i'll explain it once again. astrology and astronomy are not exactly the same. we have always been fascianted by the sky, even in the olden times. this led to the creation of many branches of studies including astrology and astronomy. even though we were right about some things in the past, we'd need a system to explain all these phenomena. this led to the starting of astrology which is a collection of practices aiming to reveal future events by studying the positions of the celestial bodies. it, in the smallest words, a search of meaning in the universe. many civilizations uch as the indians, chinese and maya developed elaborate systems for predicting events from celestial observations. astrology is classified as a psuedoscience due to lack of accuracy and lack of evidence that the motion of planets and stars will affect the lives of beings on earth. astrology was just a way for the humans of the ancient world to shift their responsibility on to the stars because no one could hold them accountable if the twinkling objects in the sky were responsible for everything.

astronomy, on the other hand, is the scientific study of the heavenly bodies in the sky. it tries to use mathematics, chemistry and physics to explain the phenemons rather than winging it. even though the indians, chinese, and the maya were ones who helpied in the beginning of astrology, they including the babylonians, greeks and native americans made methodecial observations of the happenings in the sky. it tries to focus on explaning the events with proper evidence rather than placing it on a god or a star.

beanie001 hehe, i am just an alien cat visiting. anyways, what is the universe made of, i mean what even is it?

space101 well, the universe comprises everything - all matters and energy. the field of cosmology that is the study of the universe's origins, evolution and ultimate destination, has declared that all space and time began in the big bang 13.8 billion years ago and that the universe has been expanding ever since. the structure of the universe has been thought of many times before, with some folks placing the earth in the center, talk about earth nationalism here. this is called the geocentric model. this is however false, with the sun being in the center with the earth not even being the first one around it but the thrird one. we soon learnt that the sun is just one of the hundreds of billions of stars in the milky way which is one of the hundreds of billions of galaxies in the observal universe.

due to the finite speed of light, there is a limit to which the light can travel. the spatial distance from which we can recieve light is called the observal universe. the universe is made up of 68% dark energy, 25% dark matter, 5% normal matter. when i say dark matter and energy, i don't mean that the universe is trying to edgy and emo. dark energy is an unseen and proposed form of energy responsible for the accelerating expansion of the universe. it's almost the opposite of gravity whose job to pull matter together, it causes the universe to expand at an accelerating speed. dark matter can't be directly observed because it doesn't emit, reflect or absorb light. it is the invisible glue that holds the galaxies together from flying off due to their high rotating speeds. ordinary matter is the physical substance making up all things that can be observed. it can emit and absorb light. physicists are sure they exist but still don’t fully understand what they actually are or how they work.

beanie001woah... that's dark... anyways, what do you mean the speed of light? light can travel?

space101... well. yes, light can travel. it can be an electromagnetic wave and also a photon. it can be whatever it wants, much like barbie. when atoms absorb energy, electrons get excited and jump up to a higher energy level. the electrons fall back to their orignial level, releasing energy in the form of a photon. an electromagnetic wave is the result of many photons that radiate energy through space. they are transverse waves, with electric and magnetic fields oscillating perpendicular to each other and the direction of wave motion. light travels as an electromagnetic wave, in straight lines at speed of about 300,000 km/s in a vaccum, it's the fastest in it. it can also behave like particles(photons) carrying energy directly to our eyes or reflecting/refracting off surfaces.

in astronomy, you'll hear a lot about both light years and speed of light, they're both different. light years is a unit of distance used in space, it represents the total distance light travels in a vacuum in one julian year(365.25 days). one light year would equate to 9.46 trillion kilometers, given that the speed of light is 299,792,458 m/s or 3*10^8 m/s as an approximation. yeah, space is that BIG.

beanie001well... if it takes time to travel, does it mean we are seeing them in the past?

space101yea! you got it right, actually. we are seeing things as they were in the distant past. sun's light takes 8.3 minutes to travel to the earth so, we are seeing the sun as it was 8 minutes ago. the nearest star, proxima centauri, is over 4 light-years away, meaning we see it as it was 4 years ago. so yeah, everything we see in space, is in the distant-past. it's a cool fact and also slightly poetic. somewhere out there, on a star, you'd still be young and naive. though i am not sure alien cats grow up like humans.