# Questions tagged [sun]

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17 questions
74 views

### 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 ...
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 ...
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 ...
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 ...
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. ...
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?
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.
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 ...
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 ...
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 ...
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 ...
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 ...
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 ) ?
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 ?
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 ...