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Questions tagged [sun]

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0answers
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Lighting an area of the Earth Surface from LEO

What does the math look like to calculate the size of an object in LEO that when angeled off the sun, would illuminate a part of the Earth's surface? For example, if I wanted to 'lightup' a square ...
9
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1answer
577 views

Is it possible to reach the Sun without expending any fuel/reaction mass?

Imagine that I'm designing a space probe, that will initially be placed into an Earth-like orbit around the Sun. My goal is to have the probe fly/fall into the Sun; it's allowed to take as much time ...
4
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1answer
102 views

What are the problems that need to be taken in consideration when trying to find planetary position by using jpl ephemerides?

I'm currently trying to determine the position of the sun and the moon from jpl ephemeris DE200 which is referred to the dynamical equator and equinox of 2000 and uses tdb time. I am using the j2000 ...
4
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2answers
290 views

Solar Flux on Mars Surface

Considering that the Solar Flux on top of Mars' atmosphere is 590 W/m2 (following the 1/r^2 relation for sunlight), how much of this incident light actually arrives to Mars. In other words, what is ...
2
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1answer
220 views

How quickly is the force of gravity exerted? Is a finite “speed of gravity” used in orbit calculations?

So I was reading a post of "What would happen if the sun disappeared". An excerpt: After eight minutes, the Earth would not only lose the sun's light and heat, but also its gravitational influence. ...
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0answers
82 views

Which one is older light or stars? [closed]

I kind of feel that light is older than stars. But is there any scientific theory or hypothesis on it?
11
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4answers
2k views

Is oxygen present in the sun? [closed]

If there is no oxygen in the sun, then how is it burning? My question may be weird but I need a realistic answer for that.
4
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1answer
218 views

How much radiation shielding would be required for a habitat at Mercury–Sun L5?

Given an O'Neill "Island Three" style cylindrical habitat located at Mercury–Sun L5 orbit, how much radiation shielding would be required to protect the occupants, and how would it need to be ...
3
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3answers
706 views

What dangers are astronauts exposed to when facing the sun?

In this live stream, we have an astronaut facing the sun (we've seen his hands actually): I thought people doing an EVA should avoid the sun at all cost, but here he's facing it. From what kind of ...
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1answer
147 views

Why is one of the foci of the ellipse of the trajectory of a space rocket in the center of the sun?

According to a book I am currently reading, space rockets and ballistic rockets fly along an elliptic path. However they differ in where the focus of the ellips describing their path lays. For space ...
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1answer
1k views

How to check, if there is currently an increased solar activity?

I've got an email, that because of the increased solar activity, more cosmic ray-s are hitting the earth. And for this reason, humans experience more stress and headache. I know, it's not true. But I ...
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1answer
139 views

What thermal effect does the Sun have on spacecraft that are roughly the same distance from the sun as the earth is?

What thermal effect does the Sun have on spacecraft that are roughly the same distance from the Sun as the Earth? Specifically, do spacecraft need to constantly rotate so that one side doesn't get ...
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1answer
267 views

Local Time Calculation

How To Calculate Local Time Of A Sun Synchronous Orbit With A Given Altitude ( Say 600 km ) , Inclination ( 98 degrees ) ?
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0answers
127 views

Satellite Orbit-Sun Geometry of Sun synchronous Orbit

What is the difference in satellite orbit-sun geometry of Sun synchronous orbits of 6am local time , 9 am local time , 12 pm local time ?
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2answers
122 views

Using a probe to take gravitational measurements of the interior of the sun

Could one use a space probe to orbit the sun close enough to take measurements of angular / spherical gravitational field variations similar to what Juno plans to do for Jupiter? Since the sun ...
6
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1answer
1k views

How strong is the Sun's gravity at the distance of Jupiter's orbit?

I had read that the Sun's gravity at the distance of the Earth's orbit was 0.0006 times that of Earth's gravity. So, I was wondering what it would be further out, at the distance of Jupiter's orbit.
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2answers
171 views

A probe floating in Sun's surface

Is it possible to construct a probe that would float in the Sun's surface? The temperature of Sun is 5,800 K and I heared there are alloys that can remain solid at 4500 K. I wonder if it is ...