Questions tagged [earth]

Questions of the science and space exploration related to Earth.

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If the lights we receive from old galaxies are old, could we see ours if we were in those galaxies? [closed]

I am bit of an amateur in space and astronomy. As far as I understand the light that we receive from those galaxies is old, millions and billions of years old. A galaxy that is 100 million light years ...
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3 votes
2 answers
67 views

How to calculate earth's precession using JPL Horizons System?

I'm new to JPL Horizons and understanding how to use the tool efficiently. I'm looking to extract earth's precession data and understand where we are in the current cycle. I understand we progress 1 ...
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33 votes
3 answers
5k views

Why all the 'dust' on liftoff?

To bring things back to earth (literally), why is there such a plume of what I can only imagine is dust on liftoff from launchpads on Earth? Every launch I see from Earth has a huge cloud shooting out ...
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7 votes
1 answer
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Is there a low Earth orbit with a 24-hour day night cycle?

Are there any possible low-Earth orbits that use precession to match Earth's day/night cycle? So like SSO, but specifically aimed to achieve a 24hr day/night in LEO. If so, what would its parameters ...
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51 votes
3 answers
9k views

Shouldn't space junk fall back to Earth on its own? How long will take for a ~1 cm piece of junk in LEO to fall back to Earth on its own for example?

I'm a noob in this subject and know little about space exploration, but I wonder about this every time I read the news: Wouldn't drag make all space junk fall back to Earth after some time? I'm ...
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1 vote
0 answers
93 views

Which deep-space spacecraft flew closest by Earth during a gravitational assist?

The extremely cool NASA JPL video Triumph at Saturn (Part I) is really worth a watch and/or listen. (Don't forget Part II as well!) At about 26:30 it discusses ...
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20 votes
5 answers
8k views

Are pictures of Earth' space junk realistic?

Every time I look at a picture that shows the amount of space junk I'm baffled. I can't for the life of me think how anything else being launch into orbit actually makes it without hitting anything ...
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2 votes
1 answer
193 views

How to calculate the height above the horizon of a geostationary satellite on a given latitude?

Wikipedia's Geostationary orbit; Communications says: Geostationary communication satellites are useful because they are visible from a large area of the earth's surface, extending 81° away in both ...
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-1 votes
1 answer
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Why is Aurora Australis less popular? [closed]

The Aurora Borealis(Northern Lights), in the North, gets more publicity, than the (Southern Lights) Aurora Australis, Why is it so?
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  • 153
2 votes
1 answer
181 views

Does the Moon's orbit intersect the Earth's orbit around the Sun?

I know that the Moon's orbital plane makes an angle of 5 degrees with the Earth's orbital plane or the ecliptic. Also, the Moon's orbit intersects the Earth's orbital plane at two nodes - ascending ...
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6 votes
1 answer
248 views

How can we mine Near Earth Objects?

After skimming this Worldbuilding SE answer, I wonder if any companies or space agencies have plans in place to mine Near Earth Objects(NEOs) in the future.
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4 votes
1 answer
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Biggest orbital inclination change done in Earth's orbit

Generally orbital inclination change is said to be (fuel) expensive. What is the biggest orbital inclination change (in degrees) done in Earth's orbit for an orbiting object? Can this be broken down ...
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1 vote
1 answer
696 views

How much of the total angular momentum of the Earth-Moon system is due to the Moon?

I've read that the total angular momentum of the Earth-Moon system is 3.41x10^41 g.cm^2/s (1). How much of that is due to the Moon? In other words, if the Moon ceased to exist and the Earth ...
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1 vote
2 answers
150 views

Why are minimum three artificial satellites required for radio-communication all around the Earth?

Artificial satellites orbiting the Earth have important applications for radio-communication around it. To avoid the blockage of radio-communication around the Earth, multiple satellites can be ...
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0 votes
0 answers
35 views

If I know the masses, positions, and velocities of two objects, how do I calculate their trajectories under gravity?

I was thinking about the effect of a near-miss with an asteroid upon the orbit of the earth around the Sun. My goal is to figure out a formula I could use for a visualization I'd like to build to get ...
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5 votes
1 answer
187 views

Do astronauts on ISS notice Earth's seasons?

Has anyone stationed on the ISS for some months reported noticing the changing seasons on Earth in any way like people on the surface do, subconsciously without needing to look up numbers for anything?...
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3 votes
3 answers
681 views

How to plot this orbit?

I have these data for some orbits, without any explanation about meaning of each datum: ...
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2 votes
0 answers
151 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 ...
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31 votes
3 answers
7k 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 ...
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17 votes
5 answers
4k 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 ...
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3 votes
1 answer
147 views

Should coordinate transformations from J2000 to ITRF93 in quaternions be cyclic?

I used SPICE's pxform at an interval of epochs to determine the transformation from J2000 (inertial) to ITRF93 (Earth body-fixed) frame. Then, I converted these rotation matrices to quaternions with ...
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2 votes
0 answers
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J2000 to current ECI transformation matrix

I want to find the transformation matrix that converts an ECI frame at some time 't' (lets say t = 1st January 2020) to J2000 ECI frame (that is ECI frame at noon of 1st January 2000). From what I ...
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2 votes
0 answers
66 views

Earth's Axial Precession and Frame Change [duplicate]

Is Earth's Axial Precession and change in Axial tilt values significant enough to be considered while writing Rotation matrix that converts Body frame into ECEF frame and also while propagating Orbit ...
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1 vote
0 answers
25 views

magnitude of magnetic anomalies (Earth and Mars)

I've been looking for the magnitude of highest and lowest magnetic anomalies on Earth and Mars (mapped by spacecraft in low orbit), by searching online I couldn't really find a numerical value. From ...
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10 votes
2 answers
374 views

Why do many Mars missions launch now, if the Hohmann transfer orbit is the most propellant-saving one?

The Hohmann transfer orbit is the most propellant-saving transfer orbit to Mars. When using this kind of transfer, the rover/rocket/etc. starts from Earth when Earth and Mars are in conjunction. But ...
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3 votes
1 answer
94 views

Would Earth without water look like Mars? [closed]

I was watching this slideshow of 4K images of the surface of Mars, and I noticed that the surface looked mostly smooth, with the most rugged features being crater impacts (sort of resembling an Earth ...
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1 vote
0 answers
561 views

Calculate Satellite ground track

I'm trying to find equations to calculate satellite position based on orbit parameters and given time. What I currently have is a mess that is basically giving me bunch of garbage. What is latitude ...
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1 vote
0 answers
52 views

Why spacecraft 's trajectory is shown undulating curve on 2D image of earth? [duplicate]

As i am watching live-stream of Demo-2 mission,the trajectory of a capsule is shown curved(like sin wave). In other words, why their trajectory isn't along longitude so that in 2D, the path followed ...
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3 votes
1 answer
203 views

Earth Live Video Feed in HD?

Is there any space agency that provides a live video of Earth, in HD? Preferably without anything man-made in the way (e.g some ISS robotic arm)? I want to create a live HD wallpaper of Earth, so I'm ...
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-9 votes
2 answers
347 views

Is it easier to take off from the moon or earth? [closed]

how much mass does the moon have? how much mass does the earth have? how much force needed to leave earth how much force needed to leave the moon
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18 votes
3 answers
5k 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 ...
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2 votes
0 answers
28 views

Can any aspect of the brightness of Martian twilight be determined by Curiosity's photo of Earth? [duplicate]

Curiosity took this image of Earth on Jan. 31, 2014, 80 minutes after sunset. Stellarium has the Earth >15° above the horizon 80 minutes after sunset on that day. With Stellarium indicating the ...
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2 votes
1 answer
94 views

What was the effective magnification of the Mars Reconnaissance Orbiter's HiRISE camera to acquire the detailed image of Earth?

On October 3, 2007 NASA's Mars Reconnaissance Orbiter HiRISE camera acquired this image of the earth and the moon from Mars The oceans and clouds can be easily distinguished and "the west coast ...
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7 votes
3 answers
2k 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 ...
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2 votes
0 answers
211 views

What is the acceleration necessary for a Brachistochrone transfer from Earth to Mars?

With these orbital configurations, source-Bing leaving Earth on Aug 16, 2106 and arriving on Mars October 10,2106, what is the lowest continuously-applied acceleration that can make what is ...
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15 votes
3 answers
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?
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3 votes
2 answers
1k views

How to determine the distance between where Earth and Mars are two specific dates?

How would I find the solar-system-relative distance between where Earth would be on 2106/8/16 and where Mars would be on 2106/10/16, or any combination of dates. Image source-Bing Is there software ...
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6 votes
0 answers
74 views

Could Breakthrough Starshot be used to deflect asteroids and comets?

Would Breakthrough Starshot be able to deflect an asteroid or comet? I have seen thoughts about using the lasers that would launch Breakthrough Starshot to deflect asteroids or comets: https://www....
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3 votes
2 answers
306 views

What does Earth's J₂₂ moment look like?

Wikipedia's Geopotential model give's the form of the potential component linked to $J_2$ as $$u = J_2\frac{P^0_2(\sin \theta)}{r^3} = J_2\frac{1}{r^3}\frac{1}{2} \left(3 \sin^2\theta-1 \right) = ...
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1 vote
0 answers
83 views

How much does the earth's axis change its tilt every year? [closed]

In recent years it seems that the winter sun rises and sets even further south as parts of my house are illuminated with sunlight that I don't recall 4 or 5 years ago.
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20 votes
5 answers
6k 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 ...
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1 vote
1 answer
152 views

Definition of a trans-Earth injection

Should every "propulsion maneuver used to set a spacecraft on a trajectory which will intersect the Earth's Sphere of influence" be called a trans-Earth injection? Regardless where the spacecraft ...
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33 votes
4 answers
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 ...
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31 votes
3 answers
8k 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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0 votes
4 answers
217 views

What kind of force is there in exact middle of earth? [closed]

Basically i have one question but this question leads to another. firstly can we dig in earth that from one side we reach other side of earth ? i mean just going through it. Now let's say we can dig ...
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1 vote
1 answer
514 views

Can we hang a really large rope or wire from space to the Earth? [duplicate]

I have a very simple question that can we hang a really large wire from space to the Earth? What if we build some turbine kind of thing that can produce electricity in space and we transfer that from ...
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3 votes
1 answer
225 views

Which camera has produced this image from Longjiang-2 microsatellite?

Here is an image of this lunar micro-satellite taken in 2018, from this tweet, found in this comment below the question What is the most recent photo taken from the Moon surface as of August 2019? In ...
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36 votes
4 answers
14k views

Why is my Earth simulation slower than the reality?

It took me a long time to create a simulation of the Earth like that. I wanted to show the real spinning speed of the Earth. Here's my video: From this NASA live ...
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2 votes
0 answers
117 views

Orbiting clock visible with the naked eye

Does anyone remember from the 1980s or possibly early '90s in the UK news a (serious) story about contructing a huge orbiting clock so that people would be able to look up at the sky to read the time ...
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1 vote
3 answers
412 views

Is the night sky on Earth different from the night sky on the moon or Mars?

If colonists or space-tourists spend time on the Moon or on Mars long enough to have a chance to take a good look at the nighttime sky, will they be able to see stars and the Milky Way? Will they ...
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