Astronomy Stack Exchange
Astronomy Stack Exchange

Questions tagged [earth]

Questions regarding the planet on which humans live; the third planet from the Sun.

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Why would it be very light out at 3 AM?

My brother noticed something very odd last night: it was amazingly light out when he stepped outside for a smoke even though it was between 3 AM and 3:30 AM EDST and we are near Toronto Ontario Canada, not in the Far North. He is outside at that…
Henry
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How one can establish that the Earth is round?

I am asking this question out of curiosity. Currently, I am reading the book: A Brief History of Time. In Chapter 1, the author discusses about Aristotle's conclusions about spherical Earth. For example: At horizon, one sees the top of the ship…
YII
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Why are perihelion and the shortest day in the northern hemisphere different?

The orbit of Earth is elliptical and the nearest distance to sun is perihelion position. Should it not be the shortest day in the northern hemisphere?
Mohan Mone
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Historical Day Lengths on Earth

I recently read something about a major earthquake in Japan having possibly shortened Earth's day due to an increase in rotation. Here's an example: https://www.nasa.gov/topics/earth/features/japanquake/earth20110314.html When I read some more about…
PrimeNumberHobbyist
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As days get longer, why isn't the added daylight split evenly between sunrise and sunset?

I have a basic understanding of the sinusoidal relationship of the rate of change of daylight as the year goes on. But it seems intuitive that the changes should be equally split between sunrise and sunset. For my location, Bend Or., todays…
Steve H
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What methods can high school students use to measure the radius of the earth?

I suppose they could split into 2 groups and use the shadow method from different latitudes. Maybe they could also use the stars on the horizon at two different latitudes. Is measuring a ship below the horizon feasible ? What other methods could be…
Kantura
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In astronomy Is there a name for the exact time between solar noon and sunset?

Like there are names for various events such as sunset, sunrise, solar noon, solar midnight, astro, nautical and civil twilight, what exactly is name for time between sunset and solar noon. Afternoon it is but what exactly between these two points?…
Omair
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22nd is shortest day in some places, but the 21st is shortest in other places. Can this be true?

The Winter Solstice in the Northern hemisphere in 2015 is December 22 at 04:49 UTC. Where I'm located in Nova Scotia, Canada, that's December 22, 00:49 AST. And so I would say the shortest day of the year is tomorrow, the 22nd. But for my…
David Dubois
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Is Earth's rotation Slowing down or Increasing

Recently read that Earth is rotating faster than earlier1. However so far it is understood that earth's rotation is slowing down and to conserve the angular momentum Moon is going away from the Earth. What is true? 1for example see answers and…
Mohan Mone
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What effect does the Earth's rotation have on plate tectonics?

I've been reading up on plate tectonics and found that there are several different driving forces involved. One of the main categories of driving force mentioned on Wikipedia is forces related to the Earth's rotation. The section on driving forces…
called2voyage
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seasons elongating and shortening

I have heard of years with longer summers and winters and shorter springs and falls and vice versa because of a change in the earths axis. Is this from the procession that causes the season switch every 25,800 years or is it from some other change…
Caters
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Measurement precision of celestial events

The local weatherman declared that fall starts at exactly 10:21am (local time). Ignoring the fact that seasonal boundaries have multiple definitions (meteorological, astronomical, etc.), what he perhaps means to have said is that the fall equinox…
Anthony X
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Why wasn't there any oxygen in the beginning of the Earth?

In the total beginning of the Earth there was CO2, N2 and H2O. So there was O2 but always in bond with Carbon and hydrogen, but what is the reason for that? Is O2 always reacting with free carbon atoms? The temperature of the Earth was is those…
Marijn
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The size of the Earth

Has the earth always been this size apart from a few occasional additions from time to time. Meteorites hitting the planet now don’t become part of it and the moon when it collided just spun of into its orbit. So how, as documentaries show, do…
John
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Is the flat earth cosmology scientifically justifiable today?

With binoculars or telescopes you'd be able to see to other countries if the earth were flat. And looking out at the ocean we can see where the earth curves and things like the top of ships, not the whole ship. Unless those who think the earth is…
Flat Earth
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