Questions tagged [earth]

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

28 questions with no upvoted or accepted answers
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How will the Solar tides affect the Earth's rotation once it is tidally locked to the Moon?

It is my understanding that the tidal forces of the Moon acting on Earth cause it to slow down its rotation and, because angular momentum is conserved, the Moon's orbit subsequently expands. This ...
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63 views

Simulate earth, moon, sun constellation with dates

I would like to simulate the three object distance, specifically the distance of the moon to both, sun and earth for further investigation into tide prediction. What would be a good starting point ...
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107 views

Do differentials in the Earth's density cause the flyby anomaly?

The flyby anomaly is an occasional, unpredictable, and as yet unexplained discrepancy in acceleration of satellites when they pass close by the Earth. It causes an increase of up to 13 mm/s during ...
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86 views

How does NASA estimate the size of the population of Near-Earth Objects (NEO) of diameter>140 meters?

In 2018, the US Congress passed a bill to allocate budgets and mission goals to NASA. Section 321 of that Bill mentions a goal for detection of NEOs of diameter >140 Km. Quote: (1) The George E. ...
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Other side of Earth when the Dinosaur-killer struck

When the (Chicxulub) asteroid hit Yucatan, what was it like in the minutes, days and weeks afterward on distant locations on Earth? Related How loud was the asteroid that killed the dinosaurs?
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84 views

What's the first written record of the moon being tidally locked to the earth?

I couldn't find references as to who first noticed (wrote down) that the moon was tidally locked to the Earth. This, to me, doesn't seem obvious from first glance, and looks like something only found ...
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556 views

Earth-Centered Earth-Fixed coordinates with respect to heliocentric coordinate system at vernal equinox

I am trying to calculate the position of a point on the Earth's surface with respect to the Sun's center at a certain date and time. For what I am trying to do it is OK to ignore precession of Earth's ...
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22 views

The electron–cyclotron maser emissions from Earth

The first-ever detection of radio signals caused by the electron–cyclotron maser mechanism outside of the Solar System, on Tau Bootis b was recently published (here). This phenomenon causes huge radio ...
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63 views

Has the computed change of the axial tilt ever been measured?

Earth, the 3rd planet from the Sun, sometimes faces earthquakes and seaquakes that are so strong that they reportedly change the axial tilt and/or the rotation velocity. These changes are merely ...
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55 views

Keplerian Elements for the Moon and Earth around their Barycenter

So I'm looking to replicate the inner Solar System to a decent degree of accuracy. So far I've been utilizing the Keplerian Elements and Equations for the planets, as shown here. There is one issue ...
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104 views

Orbital decay of the Earth's orbit and Earth's moving closer to the Sun

If we consider orbital decay of the Earth's orbit, then can we counter argue with the following reasons? Due to tidal effects transferring small amounts of angular momentum from the Sun's spin to ...
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198 views

How does Ptolemy prove in the following excerpt that the Earth could not be outside of the axis spanning between the poles of the celestial sphere

I have trouble interpreting the following excerpt: “Against the first of these three positions militate the following arguments. If we imagined [the earth] removed towards the zenith or the nadir ...
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103 views

How long was a lunar month in ancient times?

As the Moon is getting farther and farther from Earth, it's natural that the time it takes to circle around our planet is going to increase, thus the month will be longer. However, I read that the ...
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71 views

Calculating Angle Between Two Planets In Heliocentric Orbit

My goal is to calculate the retrograde of Mercury. What I've been working from is the book, Practical Astronomy With Your Calculator 3rd edition. I've made some progress, but I seem to be stuck with ...
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36 views

What is the period of the 'cycle' of Earth's ecliptic variation, relative to the 'invariable plane'? 70,000 or 100,000 years?

The plane of Earth's path around the Sun, the ecliptic, is different from the average of the solar system's as a whole (the invariable plane) by about 1.57°.... Our path around the Sun, though, goes ...
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130 views

How is bond albedo calculated?

According to this website, Bond albedos are computed by calculating the ratio of the flux reflected by a planet (integrated over wavelength) to the total stellar flux incident on the planet. Three ...
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59 views

Meteor size and frequency distribution for Earth vs. moon or other planets?

I struggle to find an answer to the at-first-sight simple question if or how the size distribution and frequency distribution of incoming rocks hitting the ground or the atmosphere vary from Earth, to ...
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95 views

How does earth rotation affect rain

How is rain related to earth rotation? Suppose the earth rotation slowed down gradually to a third of its current speed. Will that affect the rain? If the earth stopped rotating on its axis completely,...
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68 views

Where and when will someone on Earth be standing with the floor parallel to the Ecliptic plane?

I have been trying to figure this out and I think the answer might be - once per day for anyone living on the Tropic of Cancer or Capricorn. Is that right? To be clear - I want to know where on Earth ...
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68 views

Orbitally convenient Mars-to-Earth transit times?

Are there any peculiar solar system layouts that would result in highly efficient transits between Mars-to-Earth? I am aware of a Hohmann transfer orbit, but can other planets be used to "sling-shot" ...
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48 views

Angle of the Sun during winter solstice

What is the angle of the Sun on the eastern horizon at 35° latitude if it is the winter solstice?
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56 views

Angle between earth's angular momentum and earth's axis

I think this picture is correct because for earth astronomical day is slightly shorter than solar day. (Is it a rule of thumb for planets? Where can I read such data?) Source So the angle between ...
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116 views

Just out of curiosity. What's this curvature per unit length for a sphere? I see a lot of flat earthers using it.

I've seen most flat earthers mention if earth was a sphere the earth should curve at x value per unit length. Is that even a proper logic? Radius of curvature is constant for sphere and a circle of a ...
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30 views

What is the formula to input date, time and longitude. Where I can get latitude of the civil twilight back?

I am making a watch app, where I need to know where there is currently sun, and where it's not. I need to have some sort of formula/function to insert: date, time and longitude, and get back the ...
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93 views

What is the highest albedo of the earth's surface facing the sun ever measured?

This website (page 26) claims that full-earth-shine on the moon is 100 times greater than full-moon-shine on earth. The figure 100 is made up of the difference between the size of the earth and the ...
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44 views

How do I calculate the elevation angle to the horizon?

I'm creating an app to visualize the southern area of the moon from a first-person perspective. I'm trying to determine if a point on the surface is a "checkpoint," where the elevation angle ...
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62 views

Astronomical events and Celebrations

In the past people celebrated important astronomical events and some of those events are still celebrated in some cultures and traditions. For example: March/September equinox, New Moon, Winter/...
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176 views

Maximum and minimum masses and sizes of giant planets?

What are the minimum & maximum masses and diameters of giant planets? Minimum end of the scale Earth has mass of 1 Earth mass and a mean radius of 6,371.0 kilometers, and thus a mean diameter of ...