ChrisARippel
ChrisARippel t1_izheppd wrote
Before we had airplanes and satellites, people went around measuring the distances between objects on the land. Map makers took these measurements and made maps on the Earth's surface.
For the past hundred years, astronomers have been measuring the distances to groups of stars and their directions. Astronomers have used these measurements to make illustrations of the general shape of the Milky Way.
Is it perfect? No, astronomers are still discovering features of the Milky Way, such as the wave in the disc.
ChrisARippel t1_iymd9yx wrote
Reply to Is it possible that nuclear defense technologies will surpass the abilities of nuclear weapons in the future, rendering them near useless? by Wide-Escape-5618
Even if we developed the capacity to shoot down current ICBMs, do you think adversaries would not find another way to deliver them?
ChrisARippel t1_ixulse1 wrote
Reply to comment by zambabamba in Correct me if i'm wrong, but need some people smarter than me to answer these questions about "The Big Bang". by zambabamba
I like Don Lincoln videos.
I get several things from this video.
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Astronomers can see the CMB, visible 380,000 years after the Big Bang.
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Explanations of the early universe from 380,000 years ago to 10-13 seconds after the Big Bang are based on observations in particle accelerators creating the hot, energetic conditions of the early universe. My point is that these explanations of the time before what astronomers can observe with telescopes are NOT only mathematics as some appear to claim.
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Explanations from 10-13 to 10-43 seconds after the Big Bang are mathematics based on known laws of physics.
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Known laws of physics break down at 10-43 seconds after the Big Bang. Descriptions of the universe before 10-43 are only speculation which at best don't contradict known observations, physics and mathematics.
ChrisARippel t1_ixk3v7j wrote
Jupiter's stripes are officially called "belts" and "zones". The "zones" are updrafts that are taller than the downdrafts of the "belts". Together they form a convection current like on Earth. Source: scroll down halfway down the page to the illustration of belts and zones.
ChrisARippel t1_iwunv7t wrote
I thought the answer should be "bad".
ChrisARippel t1_iwbz3wb wrote
We are on a spaceship.
The Solar System is traveling at 828,000 km/hr (514,495 mph) through the Milky Way. When you look at night sky the stars you see are the large, close stars less than 5000 light years away.
Do you notice stars whipping past?
Traveling on human-made spaceships would look similar, especially if the ship rotated around its axis to create artificial gravity.
ChrisARippel t1_iuf9szp wrote
Reply to comment by Cevvi in If the Milky Way is located in the middle of a void, does this explain why we see no aliens? by [deleted]
I don't rule out the possibility of advanced civilization in the galaxy. The idea of a galactic civilization seems silly to me. Vastness of the galaxy you mentioned is one point. My point is why?
The Europeans looked for India and China because that is where the good stuff was and they wanted it. I think we imagine aliens would be explorers like Europeans.
The way more advanced Chinese had an earlier age of exploration in giant ships. They were generally unimpressed with what they found. Everywhere else was poorer and less advanced. They halted further exploration. An advanced alien civilization might be like Chinese and see little point in exploring the entire galaxy. The knee-jerk answers are more resources or curiosity.
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How many planetary systems would an advanced civilization actually need?
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How many planetary systems does an advanced civilization need to explore before it's been there, done that?
ChrisARippel t1_iue8833 wrote
Reply to Please explain in simple words by Tatti_luck
Don Lincoln's videos help me answer your questions
ChrisARippel t1_iue6qxb wrote
Reply to comment by Cevvi in If the Milky Way is located in the middle of a void, does this explain why we see no aliens? by [deleted]
I think you overestimate our technology's ability to detect life.
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We have detected 5000 exoplanets within 5000 light years of Earth.
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Our technology to see these exoplanets is very primitive.
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Our current technology could detect Jupiter and Saturn, but not the terrestrial planets in their locations in our Solar System.
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Since our technology can't even detect Earth, no way could our technology detect life on Earth.
I think you are jumping to conclusions without sufficient evidence.
ChrisARippel t1_iudssc8 wrote
Reply to If the Milky Way is located in the middle of a void, does this explain why we see no aliens? by [deleted]
The Milky Way has 100 to 400 billion stars. We are not seeing aliens from Milky Way stars. This is the Fermi Paradox that needs explaining.
ChrisARippel t1_iu6ao1t wrote
The Zodiac constellations are associated with different months because as the Earth revolves around the Sun, the Sun blocks the Earth's view of the constellation associated with that month.
For example, my birthday is September 17. I am a Virgo. The reason I am a Virgo is because the Sun blocks Virgo during September. In October, the Earth's orbit makes the Sun block another constellation and Virgo can be seen again.
In summary, the Earth's orbit makes different constellations and their stars visible through the year. So there are seasonal constellations.
ChrisARippel t1_isvkk0q wrote
Reply to Confusing Question. by jtlickl1
The vertical axis is the escape velocity in kilometers per second.
The horizontal axis is surface temperature in Kelvin.
Surface temperature causes gas atoms to speed up. The higher the temperature the faster the speed.
Simply speaking, if the speed of gas atoms caused by the surface temperature exceeds the escape velocity caused by gravity, gas atoms float off into space.
The so-called vacuum of space happens because gravity attracts more gas atoms to stars, planets, moons, asteroids, comets, etc. than are floating in the space between these objects.
ChrisARippel t1_issu3w2 wrote
Reply to How can we know details about animals that lived thousands of years ago if all we have are bones? by DemetrioGonz
We also have
And fossils and traces of the environment.
ChrisARippel t1_is6r6nt wrote
Reply to How do we know the exact color of things? by ItzzStrike
There is no exact color of things.
Colors of objects depends on the wavelengths of light emitted by objects and the interpretations of those wavelengths by eyes and brains.
Point 1.
Light wavelengths are real, but colors are interpretations of eyes and brains.
Light comes in a wide range of wavelengths. Human eyes see wavelengths between 400 and 700 nanometers. Bees see light from 200 to 600 nanometers. See the third image on this page.
Different wavelengths of light stimulate cones in the eyes of human and bees. This stimulation is interpreted by the human and bee brains as colors.
Look at the image on this page. The top row is how these flowers look to humans. The bottom row is how the same flowers look in ultraviolet which bees can see.
So which is the "real" color of the flowers? What humans see? Or what bees see?
Point 2.
Your point that the wavelengths of light shone on objects changes the wavelengths of light reflected off objects that reaches our eyes.
Point 3.
As objects get hot, they can emit more than reflected light, and start emitting their own light at different wavelengths depending on how hot they are. This called black body radiation.
Look at image on this page. Near the center of the image is the vertical rainbow showing where the visible light our eyes can see is. At room temperature, 294° kelvin, objects are emitting wavelengths of reflected light that we can see with our eyes.
As objects, e.g., piece of metal, heat up to say 3000° Kelvin, objects glow red because the strongest wavelengths of visible light are at the red end. At 6000° Kelvin, objects glow white because wavelengths of visible light are equal across across all visible light spectrum. At 10000° Kelvin, objects appear blue because the strongest wavelengths of visible light are at that end of the spectrum.
ChrisARippel t1_irkxmhs wrote
It takes sunlight 8 minutes to reach Earth.
Radiation from the supernovae would destroy the Earth in 8 minutes.
ChrisARippel t1_iqvlqcv wrote
Reply to If objects in space are far away, does light get scattered enough that it would look “low resolution” by the time it reaches us? by hau2mk7pkmxmh3u
Others have mentioned that light doesn't scatter in a vacuum.
However, light gets dimmer with distance. according to an "inverse square law". This has at least two implications.
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Astronomers must use wider telescopes and leave the camera open over a longer time to capture enough light to see stuff far away.
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Astronomers can use increasing dimness at greater distances to measure distance. In 1924, Edwin Hubble used the increasing dimness of Cepheid variable stars in the Andromeda Galaxy to claim the Andromeda nebula was actually another galaxy outside the Milky Way Galaxy. Source
ChrisARippel t1_j1q3ws3 wrote
Reply to A different view about the expanding space by Jacktemmink
Scenario 1 began with a Big Bang when space started expanding, creating more actual space between objects forming within that expanding space. This produces a CMB radiation and cosmological redshift both of which we have observed.
How does scenario 2 work? The universe starts already huuuuge. And objects in the early universe must also start out huuuuge so they shrink for at least 13.8 billion years. How would scenario 2 create the observed CMB radiation and cosmological redshift?