Questions tagged [satellite]

Questions regarding an object orbiting around another object due to the force of gravity.

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29
votes
4answers
3k views

Why does the Moon appear gray when passing between the Sun and the Earth?

Shouldn't the Moon appear as bright as a full Moon seen at midnight from Earth? The photo was taken by DSCOVR at Lagrange point 1. In the picture, The Moon appears dark gray. Of course the Earth ...
10
votes
1answer
2k views

Line of lights moving in a straight line, with a few following

My husband and I have just seen a line of about 15 lights moving in a straight line, quite high above the cloud level with a gap, and then 5 lights, a gap, another few, a gap, 1 light, a gap, and a ...
10
votes
1answer
2k views

Are satellites orbiting around earth visible to the naked eye?

I was just lying under the sky trying to possibly see some meteorites, unfortunately never seeing any I might add, but I saw three objects all moving at about the same speed( all at different times). ...
9
votes
1answer
2k views

Which Saturn satellite passes closest to Saturn's rings and at what distance?

I was using Stellarium to watch Saturn from its moon Pan and I saw the rings were very close to this moon. Now Saturn's rings extend for a large distance so several moons see them from close. I was ...
9
votes
1answer
2k views

What is the difference between Sphere of Influence and Hill sphere?

Wikipedia's definition of Hill sphere is: An astronomical body's Hill sphere is the region in which it dominates the attraction of satellites. To be retained by a planet, a moon must have an orbit ...
9
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2answers
346 views

Calculating the apparent magnitude of a satellite

I'm writing a program that involves calculating the apparent magnitude of satellites from a ground location. I currently have the intrinsic magnitude of the satellites and the solar phase angle in ...
7
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5answers
309 views

Are multiple geostationary satellites required to handle arbitrary locations?

Do geostationary satellites need to have the equator as the plane of rotation, and the earth's centre to be the centre of rotation? Can it rotate over, say, the Tropic of Cancer, focusing on a single ...
7
votes
2answers
569 views

Why do some artificial satellites decrease and increase in brightness multiple times?

I just observed a satellite almost directly above me travel for a few minutes while constantly dimming and then getting brighter. It did this for about 3 minutes until it faded out. I also observed a ...
6
votes
1answer
665 views

Will JWST be as durable as the hubble telescope?

JW Space Telescope is designed for a 5-10 year mission duration. Seeing as Hubble and other space missions have paved the way for JWST for reliability issues, It even has zero friction gyro's with 100+...
6
votes
1answer
134 views

Computing orbit positions of Jovian Satellites / Moons using JPL data

I've been trying to build a model of the solar system in a game. Thus far I've succeeded in placing each of the planets in position using Keplerian elements and formulae from https://ssd.jpl.nasa.gov/...
5
votes
1answer
54 views

How many (or percentage) satellites of Solar system planets have their orbits synchronized like the Moon (always facing earth)?

Mercury and Venus have no satellites. Then earth has moon (synchronized orbit). For Mars - both its satellites (Fobos and Deimos) also synchronized. Analyzing other planets is hard - too many ...
5
votes
2answers
112 views

Terminology: Is there a name for the points on the surfaces of tidally locked parent/satellite bodies that always face each other?

This is purely a question about terminology, one that has eluded my googling efforts. When a satellite and its parent body are tidally locked to each other, there is (in an ideal case) a single ...
5
votes
1answer
191 views

Maximum Amplitude of a Lissajous Orbiting Object in a L4 or L5 Position

I stumbled on The Lagrangian points during some wikipedia reading. After looking at the gravity contours, I naturally come to the conclusion that the L4 & L5 should have a wave pattern and then ...
4
votes
1answer
153 views

What were the 2 satellites I saw this morning?

This morning at 6:03am Israel time (3:03 UTC) I saw, simultaneously, what appeared to be 2 satellites streaking across the sky directly overhead. If I remember correctly, they were both coming from NW ...
4
votes
1answer
84 views

Altitude of Midnight Satellite?

The other night, I observed what I believe must have been a satellite, however it was at 1:30am so I was not sure that this would be possible. Being in the Southern Hemisphere we are just past Summer ...
4
votes
1answer
262 views

How large could a second moon of Earth be?

Question in the title. Let's say that I have a lot of garbage- mined-out asteroids, spent nuclear fuel, satellite debris, and just general trash. Also safe ways to get these into Earth orbit. Instead ...
4
votes
0answers
81 views

Bright, brief light in sky this morning (daytime) - satellite flare? [duplicate]

This morning at 8:00am UK time, give or take about 3 minutes, I saw a very bright light in the sky which seemed to get a little brighter, lasting for maybe 5 seconds after I first noticed it, then ...
4
votes
0answers
100 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 ...
3
votes
2answers
6k views

How many satellites orbit the Earth? At what rate do they orbit the earth? [closed]

I was looking at a full moon the other night with my telescope and noticed a black dot move across the moon quite rapidly. This happened a few times and others who were with me were able to confirm. ...
3
votes
1answer
242 views

Can the Moon provide momentum to an object in Earth's orbit? Gravity Assisted Boost [closed]

Can a satellite maintain an equatorial orbit around Earth near the Moon's orbit to receive partial gravitational boosts by gaining momentum as the satellite passes though the Moon's gravity well? I'...
3
votes
1answer
482 views

Are ascending node of sun, the point of intersection of prime meridian and equator and center of earth all collinear?

I did a bit of googling but couldn't find the exact answer, so are the following 3 points collinear or not ? 1_center of earth 2_ascending(or descending) node of sun 3_point of intersection of ...
3
votes
1answer
469 views

Declination calculation

My task is to calculate current declination and right ascension for some artificial Earth satellite. For example ISS. I am using latest TLE data for extracting keplerian orbital elements and then ...
3
votes
1answer
313 views

Help converting ECI to RA DEC

Using the library OrbitTools I can input a TLE and get back ECI coordinates. I want to find the RA DEC though, so I use ...
3
votes
1answer
203 views

Unknown moving objects [closed]

Last night, I used my new Sony WX500 camera to get long exposure pictures of the sky from my backyard. I used the "Heavens Above" app to find out when satellite flares would happen and I even got a ...
2
votes
3answers
170 views

Problem about orbiting of a satelite

Problem: There is an satellite that orbits the Earth. Its orbit is circular and its orbital plane is perpendicular to Earth's Equatorial Plane. It orbits is such that a person who is on equator see ...
2
votes
1answer
340 views

The dark side of the moon [duplicate]

I encountered this statement that the dark side of the moon is hidden from our sights. Could someone please explain?
2
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1answer
109 views

How come the Sun does not make the Moon crash on the Earth?

As the Moon loops around the Earth, on one side of the Earth it moves toward the Sun (let's call it downward side) and on the other side it moves away from the Sun (let's call it the upward side). ...
2
votes
1answer
89 views

Why do satellites with greater altitude travel at a slower speed?

For example, a geostationary satellite travels slower than the ISS. What is going on?
2
votes
1answer
270 views

Magnitude, satellite flare and the Heavens Above app

On the Heavens above app for Android and maybe iOS, it shows negative magnitude values for Iridium satellites, but for other ones, it shows positive. Here is a screenshot Why is this?
2
votes
1answer
55 views

Is there a reason why the IAU differenciates objects in the SS orbiting the sun into a particular classification but it doesnt for satellites?

The IAU has different classifications for objects in the solar system orbiting the sun, they can be according to their shape and if they clear their neighborhood of other material around its orbits , ...
2
votes
1answer
710 views

where to obtain ephemeris data for geodesy satellites?

Is anyone aware of where one can obtain ephemeris data in Geocentric Celestial Reference Systems (GCRS) coordinates for a geodesy satellite such as LAGEOS (It doesn't really matter which mission)? Or, ...
2
votes
1answer
888 views

Derivation of the formula for longitude of ascending node for a satellite

I've been looking into the document IS-GPS-200H to understand how to calculate satellite location in the ECEF coordinate. I am having problem understanding the formula to derive $\Omega$, the ...
1
vote
2answers
260 views

Calculate eclipse days and duration of satellite

If a satellite is revolving in a GEO orbit, then what will be the eclipse duration for it? How to calculate when the satellite will enter the dark side of the Earth? Any formula or online tool would ...
1
vote
1answer
4k views

Please help explain this unknown light in the sky. Not ISS. Not a star or comet. Too slow [duplicate]

So a few nights ago I walked outside on my front lawn and sat down on the tailgate of my truck. I was facing north. I was looking down and towards the house across the street. Out of no where a bright ...
1
vote
1answer
74 views

How to understand orbit definitions

I've been reading about satellite observations (such as this one). The writer uses terms such as these to define the orbit: ...
1
vote
1answer
190 views

what is a MIA satellite

I came across this sentence in a magazine: We sit outside the Lorne Community Hall, Victoria, watching the MIA satellite overhead. I wonder if the author is talking about an artificial satellite. ...
1
vote
1answer
301 views

How to get ephemeris data for location?

How can I obtain ephemeris data which fits to a specific location? Differently phrased: I need ephemeris data of satellites which orbited a specific location. Is there a document where I can look up ...
1
vote
2answers
82 views

How to find the radius of a satellite not knowing the mass

If I know the semi-major axis, the density of the planet, and orbital period.. how can I find the radius of the satellite? I can't think of any formula to use.
1
vote
1answer
66 views

What am I looking at?

I am in Northampton England and every night in the SW sky is a very bright, white light that twinkles. It visibly appears to be moving towards the west but appears pretty much the same start place ...
1
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0answers
22 views

Tools and algorithms for angles-only orbit estimation

I've seen discussion threads where amateur astronomers estimate a satellite's orbital parameters from angles-only telescope observation. Are there any community tools or algorithms to help with this ...
1
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0answers
30 views

What is the detector size of LANDSAT 8's detector array?

According to the suggested tags, this must be the right forum: I found that for each band of Landsat 8 over 7000 detectors are on the array. Does anyone know how big each of the sensors is?
1
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0answers
17 views

How can exoplanet moons be detected? [duplicate]

How can exoplanet moons be detected? Are there current methods to differentiate exoplanets with moons and exoplanets without moons? Or, are only the combined masses of the exoplanet and its moons ...
1
vote
1answer
53 views

Do planetary magnetic fields slow the movement of conductive extraplanetary moving objects via induction?

A fixed magnetic field will induce an electrical current in a conductive object moving through the field. The strength of the eddy currents will depend on the shape and composition of the conductor ...
0
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2answers
83 views

Polar satellites for Global Navigation Systems

Why do we need 7 polar satellites for a navigation system like the Indian Regional Navigation Satellite System (IRNSS)?
0
votes
1answer
130 views

Travelling, flashing Star? [closed]

I have recently gotten into observing the night skies and learning about the stars/ star systems that are visible to me using an app on my phone. For the last month or so Venus and Mars appear in the ...
0
votes
2answers
102 views

Actual observable horizon for satellites on an orbit line map?

On a casual star walk, (for comparison of identifying different objects) I witnessed some meteors, quite a few satellites gliding on their smooth and straight trajectories, and some airplanes with ...
0
votes
1answer
46 views

Computing the local orbital frame vector directions in a geocentric reference frame

In the context of the study of a cubesat (little satellite), I am asked to define the local orbital frame and compute the local orbital frame vector directions as a function of time : Here the ...
0
votes
1answer
41 views

Calculate eccentricity from apside altitudes? [closed]

I need to calculate the eccentricity of a satellite orbit with only the apside altitudes (height above the surface of the Earth), 400 and 1500 km. However, I don't know the semi-major axis ($a$) or ...
0
votes
2answers
141 views

Confusing satellite-like object seen in night sky [closed]

I was staring up at the stars around 11:30 PM and noticed an object moving. It had no lights, and was not bright whatsoever. It was moving smoothly and in a straight line, except extremely fast, and ...
0
votes
1answer
141 views

A strange star-like object [duplicate]

So it was around 6 AM and i was looking at the sky and there were not many visible stars because the sun was about to rise. There were two stars that were brighter than the others and i was looking at ...