Units of length | Units of measurement in astronomy
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (9.46×1012 km), or 5.88 trillion miles (5.88×1012 mi). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the time-measurement word "year", the term light-year is sometimes misinterpreted as a unit of time. The light-year is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years) which derives from astrometry; it is the distance at which one astronomical unit subtends an angle of one second of arc. (Wikipedia).
http://www.teachastronomy.com/ The vast distances to the nearest stars encourage astronomers to use a new unit of distance. Whereas meters and kilometers work well on the Earth, and the astronomical unit is the appropriate unit for scales within the solar system, the distance scale to the
From playlist 14. Stars
How Much Stuff Is In A Light Year?
Even though the name is a little confusing, you probably already know that a light year is the distance that light travels in a full year. At speeds of almost 300,000 kilometers per second that gets you pretty far from home. So take that distance and turn it into a cube, each side one lig
From playlist Guide to Space
Astronomy - Ch. 2: Understanding the Night Sky (19 of 23) Tropical Year vs Sidereal Year
Visit http://ilectureonline.com for more math and science lectures! In this video I will explain the difference between a tropical year vs a sidereal year.
From playlist ASTRONOMY 2 THE NIGHT SKY
Subscribe to our YouTube Channel for all the latest from World Science U. Visit our Website: http://www.worldscienceu.com/ Like us on Facebook: https://www.facebook.com/worldscienceu Follow us on Twitter: https://twitter.com/worldscienceu
From playlist Science Unplugged: Physics
Episode 3 of 5 Check us out on iTunes! http://dne.ws/1NixUds Please Subscribe! http://testu.be/1FjtHn5 Human perception of light is extremely limited. From gamma rays to radio waves what we see is only a sliver of the electromagnetic spectrum. + + + + + + + + Previous Episode: We Sti
From playlist Light And The Human Experience
Please Subscribe! http://testu.be/1HV4rBv Check out yesterday’s video: http://testu.be/1Jdh50f Sure, Mars may be 4.35 Light-Minutes away, but did you know that a Light-Year is actually a unit of distance? TestTube 101 is a new series that explains everything you wanted to know about the
From playlist Earth 101
2017 Total Solar Eclipse in the U.S.
On Monday, August 21, 2017, the Moon will pass in front of the Sun, casting its shadow across all of North America. This will be the first total solar eclipse visible in the contiguous United States in 38 years.
From playlist Great American Solar Eclipse Playlist
Radius of observable universe | Scale of the universe | Cosmology & Astronomy | Khan Academy
Radius of Observable Universe. Created by Sal Khan. Watch the next lesson: https://www.khanacademy.org/science/cosmology-and-astronomy/universe-scale-topic/big-bang-expansion-topic/v/correction-radius-of-observable-universe?utm_source=YT&utm_medium=Desc&utm_campaign=cosmologystronomy Mi
From playlist Cosmology and astronomy | Physics | Khan Academy
Spacetime and the Twins Paradox
An explanation of spacetime, the twins paradox which results from a moving clock running slow, and the possibility of forward time travel - but no return journey!
From playlist Special and General Relativity
How Far Can You Travel? Voyaging Billions of Light Years in a Human Lifetime
If you accelerate at 1G, you can create artificial gravity inside your spaceship. And there’s the added advantage that you can cross billions of light years within a human lifetime. How far can we travel? Support us at: http://www.patreon.com/universetoday More stories at: http://www.univ
From playlist Space Exploration
We can see things moving faster than light
How is it possible for galaxies and objects in space to move away from us faster than the speed of light? Will we ever see those objects? Check out 3M's Young Scientist Challenge! https://bit.ly/3MxDianna Support Physics Girl videos → https://www.patreon.com/physicsgirl Special thank you
From playlist Space and the Universe
Intergalactic scale | Scale of the universe | Cosmology & Astronomy | Khan Academy
Intergalactic Scale. Created by Sal Khan. Watch the next lesson: https://www.khanacademy.org/science/cosmology-and-astronomy/universe-scale-topic/scale-earth-galaxy-tutorial/v/hubble-image-of-galaxies?utm_source=YT&utm_medium=Desc&utm_campaign=cosmologystronomy Missed the previous lesso
From playlist Cosmology and astronomy | Physics | Khan Academy
Why Do We See Things Traveling Faster Than Light? Superluminal Motion Explained
Get a Wonderful Person Tee: https://teespring.com/stores/whatdamath More cool designs are on Amazon: https://amzn.to/3wDGy2i Alternatively, PayPal donations can be sent here: http://paypal.me/whatdamath Hello and welcome! My name is Anton and this is an old video I found in the archive th
From playlist Mysteries of the Universe
How Far Back Are We Looking in Time?
When we look out into space, we're also looking back into time. Just how far back can we see? Support us at: http://www.patreon.com/universetoday More stories at: http://www.universetoday.com/ Follow us on Twitter: @universetoday Follow us on Tumblr: http://universetoday.tumblr.com/ Like u
From playlist Cosmic Microwave Background Radiation
Can You Believe It? #36 What is Space (12 of TBD) How Big is Our Visible Universe?
Visit http://ilectureonline.com for more math and science lectures! To donate: http://www.ilectureonline.com/donate https://www.patreon.com/user?u=3236071 (#12) We will learn about the size of the visible universe and how it was calculated. Previous video in this series can be seen at:
From playlist CAN YOU BELIEVE IT?
What proof is there that the universe is evolving? | Michelle Thaller | Big Think
What proof is there that the universe is evolving? New videos DAILY: https://bigth.ink Join Big Think Edge for exclusive video lessons from top thinkers and doers: https://bigth.ink/Edge ---------------------------------------------------------------------------------- Light moves at 186,0
From playlist The universe explained | Big Think
Get Surfshark VPN at https://surfshark.deals/universe - Enter promo code UNIVERSE for 83% off and three extra months for free! -------------------------------- If you like this video, check out writer Geraint Lewis´ excellent book, co-written with Chris Ferrie: Where Did the Universe Come
From playlist The Entire History of the Universe
Why The Shortest Day Of The Year Isn't The Coldest
Watch the new season of MinuteBody - and get access to both CuriosityStream and Nebula - at https://curiositystream.com/minuteearth. The way we experience seasons don't necessarily line up with how they're technically defined - here's why. LEARN MORE ************** To learn more about thi
From playlist Society, Culture & Technology