Questions tagged [earth]

Questions of the science and space exploration related to Earth.

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6
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2answers
761 views

Physical meaning of perigee advance

I'm starting to study orbital perturbations and I can't find any physical explanation about the perigee advance (apsidal precession) when considering Earth oblateness effects. Can someone give a ...
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2answers
582 views

What is the Fischer 1960 Mercury Ellipsoid, and why is it called that?

Don't be distracted by the 1960 Mercury shown below. Reading about Irene Fischer (also here, and mentioned in this answer) and seeing the Fischer 1960 Mercury Ellipsoid turn up in tables of ellipsoid ...
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2answers
884 views

What Earth gravity model is used for different types of calculations?

When performing orbital calculations, under what circumstances should I assume: a perfectly spherical Earth a reference ellipsoid a geoid no particular format at all
8
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1answer
2k views

What is the brown band in which we find the pale blue dot that is Earth?

In the famous "pale blue dot" picture: we see Earth in a brown band. What is that band? Is it an artifact of the camera? Is it a ring of dust orbiting around the Sun akin to the rings of Saturn and ...
36
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2answers
5k views

Was the “Earthrise” witnessed by Apollo 8 the first available “full” photo of the Earth?

Was the video/photos taken during the earth-rise on the Apollo 8 flight the first "blue marble"-esque photo? I've heard the image equated to the "earth's first selfie" and question the technical ...
26
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3answers
3k views

Is it possible to have an orbit around the earth and the moon

I was just wondering if it were possible to A) Orbit the moon and earth B) To orbit any two celestial bodies really?
13
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1answer
1k views

Are there any proposals for a permanent orbital interplanetary ferry?

I believe I read in a book once a description of a kind of interplanetary ferry that would orbit the sun and regularly pass different planets like Mars and Earth. The idea of the ferry is to have a ...
4
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2answers
4k views

Earth angular size looking from the ISS

Imagine you're, well, actually on the ISS so you're 395 km up. We've all seen many photos roughly like this... however this can be deceptive; They might be all fisheye lenses. A great many of these ...
8
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3answers
3k views

Why is the earth so small when observed from the moon?

I recently discovered the pictures from DSCOVR taken at the Lunar Transit in 2016. The earth appears very massive behind the moon, which is a little unintuitive if you consider how small it is when ...
5
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2answers
892 views

Extinction asteroid (10-100 km) impact avoidance

With the present "state-of-the-art" of space technology what is possible to do to avoid an Earth impact by rocky bodies 10 km to 100 km in diameter? Is there any international project to develop a ...
2
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4answers
2k views

Where can the term “Sol” used?

Alright, I know that "Sol" is used on Mars to count days. But is the sun called: "Sol"? And can you use that term on Earth as well? The reason for the question is that the term "sol" is used in two ...
8
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4answers
7k views

Is it possible to touch stars with our bare hands?

Well I'm new to Space SE and have gone through many questions but I couldn't help but notice that is it even remotely possible that one can touch the stars without burning him/her self ? Is there any ...
4
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1answer
697 views

Are we changing Earth's rotation?

Can rockets launching change Earth's rotation, and can going into orbit do the same?
3
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2answers
2k views

Launching a rocket from a weather balloon for a very small payload

I am new to the site and am unaware of the correct formation of my question. That being said, I wanted to know if this is plausable and what would be the correct way of tackling this idea. If I had a ...
-1
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2answers
149 views

Faster alternative to travel to any location in the west

Suppose one needs to travel to Somalia from Indonesia(which are approximately at a distance of $4000$ miles from each other on the line of equator). To accomplish this task, I suggest the following ...
33
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4answers
5k views

What is the largest piece of space debris volumetrically?

What is the largest piece of space debris currently in Earth orbit by volume? Space debris is not limited to defunct satellites, but also includes things like spent upper stages. Bonus points for ...
27
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3answers
5k views

What does the Sun-Earth-Moon system look like from the Sun-Earth L-2 point?

The L-2 point of the Sun-Earth system is away from the Earth on the night-side of the Earth; i.e. it's always local midnight at the sub-satellite point. This is an attractive property for some ...
4
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1answer
334 views

Earth-based microwave radiometer for the Moon

Microwave radiometers (MWR) can be used passively, to get regolith's thickness, brightness temperature and dielectric constant. Apart from that, I have little idea of how the instrumentation's ...
31
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3answers
6k views

Does it make any scientific sense that a comet coming to crush Earth would appear “sideways” from a telescope and on the sky (from Earth)? [closed]

In multiple different movies and fiction, there's the threat of a burning space comet heading for Earth, threatening to kill everyone and destroy the planet. One example is the animated Comet in ...
27
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3answers
7k views

How are astronauts in the ISS protected from electric shock?

On Earth, most of the electrical appliances having exposed metal parts, such as electric iron, are grounded, to protect the user from electric shock when an uninsulated-wire accidentally comes into ...
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5answers
5k views

Is a midspace space station between Earth and Mars practical?

A recent answer included the following: For example if you were to start a colony on mars, in this order for supplies and other necessities to be delivered there would need to be a network of space ...
17
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3answers
4k views

If the Earth spun clockwise, how would that affect Space Exploration?

If viewed from the North Pole, the Earth spins counter-clockwise. Because of this, many satellites also orbit in the same direction as you can take advantage of the Earth's rotation and essentially ...
14
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3answers
3k views

Earth Moon Pork chop plot

Does pork-chop plots exist for Earth-Moon System? I could only find pork-chop plots for Earth-planet systems.Could someone please shed some light on this topic?
12
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2answers
697 views

What existing life on Earth is best suited for the Martian environment?

What existing life on Earth is best suited for the Martian environment? By best suited, I mean it could theoretically be placed on Mars and easily adapt or thrive within the existing environment the ...
2
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2answers
342 views

Are there any protocols the space station follows if there is an Earth-wide catastrophe?

Are there any protocols the space station (or any space explorer) follows if there is a massive catastrophe on Earth where the responsive parties on the ground would not be available for support/...
2
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0answers
44 views

How to convert body coordinate from Sun reference frame to Earth reference frame?

I have the coordinates of a celestial body w.r.t. Sun , expressed as (x,y,z), at a given time. I need to move this coordinates into a reference frame centered on Earth center, but after reading dozens ...
17
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5answers
3k views

Is Mohs scale of mineral hardness applicable for rocks and minerals of terrestrial planets other than Earth?

The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Now there is ...
9
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2answers
3k views

What is the effect of gravity slingshots around Earth on Earth's rotation and orbit time, and is this effect worth considering?

Several space probes have used gravitational slingshots around Earth as part of their mission plan to get to other places in our solar system. Some examples I could find quickly are Galileo, Messenger ...
7
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3answers
1k views

Could the Apollo astronauts distinguish Earth's continents and oceans from the moon?

This article "Earthshine Reflects Earth's Oceans And Continents From The Dark Side Of The Moon" indicates that the difference in reflection of light from the Earth’s land masses and oceans can be seen ...
4
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1answer
227 views

At what point when travelling faster and faster around the earth are you not gonna be falling back again (7km/s? 8km/s?)

My dad and I thought about a problem we had when discussing Earth's gravitational field. This wasnt the original question but I still would like to know the answer. So essentially my question is: ...
3
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1answer
181 views

Have there been any spacecraft with an ecliptic Earth orbit?

Have any spacecraft (manned or unmanned) orbited the Earth in the same plane as the Sun? (Please read the question carefully. It is not an orbit centered around the Sun, nor an equatorial orbit.)
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2answers
405 views

synchronized orbit between Earth and Moon

Is it possible to have a synchronized orbit between the Moon and the Earth, using the gravity of both bodies to hold its position (with some assistance, since the Moon's orbit is not circular). This ...
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3answers
876 views

Help computing solid angle subtended by the Earth as seen from LEO

I would need to compute the solid angle of the Earth from a spacecraft when close to the Earth, where no small angles approximation can be made. I thought it wouldn't be that hard but I feel actually ...