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1answer
34 views

How are microlensing events used to constrain the size of innermost stable circular orbits around spinning black holes?

The third paragraph of the introduction to the ArXiv preprint Constraining Quasar Relativistic Reflection Regions and Spins with Microlensing says: Quasar microlensing has significantly improved ...
1
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3answers
91 views

What effect does Earth losing a part of its mass have, is there an impact on the Earth's orbit around the Sun?

This is a random question that popped into my mind. I'm not a physicist or astronomist, however, I am genuinely curious. Also, this is not intended as a science fiction question, but an actual science ...
1
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0answers
37 views

What compounds are present in 3C273?

Anyone know if we have any chemical reactions occuring in this quasar?
0
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0answers
19 views

For what kinds of solar research does observing a total eclipse during a sunspot minimum “reduce the amount of 'clutter'”?

The recent Wired.com article A Drone, a $12,000 Lens, and the Magic of a Total Solar Eclipse describes the author's photo session of the recent total solar eclipse at the Cerro Tololo Inter-American ...
1
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2answers
94 views

Sagittarius star cloud?

I was using SkySafari with my phone, but the compass didn't quite work. So as I knew where the cardinal points were, I think I have shot the Sagittarius star cloud, at least a part of it. Can you ...
1
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1answer
92 views

What keeps the planets of the solar system moving in their fixed orbits?

Models of the solar system show each planet moving around on its own orbit. Is is really because of the Sun that every planets remains in its own fixed orbit?
2
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1answer
61 views

Validity of ephemeris time

In the wikipedia article for epmeris time as first adopted in 1952, it does not explain clearly how or why it was supersed ed. For example, it reads: In 1976 the IAU resolved that the theoretical ...
7
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3answers
2k views

Attach a visible light telescope to the outside of the ISS

Visible light imaging of the heavens is limited on Earth primarily due to the atmosphere. I know the ISS is moving at 17000mph, but given the delays to the James Webb telescope, is there any merit in ...
3
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4answers
118 views

Is Digital Adaptive Optics Possible?

Adaptive optics generally apply slight changes to mirrors to account for atmospheric turbulence. These generally require either a mirror to be broken up into smaller mirrors, each with their own ...
1
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1answer
112 views

Time taken for journey to the moon [closed]

India is going to launch a spacecraft to the moon on 16 July which will consist of a lander, an orbiter and a rover. I found an article in today's newspaper regarding this. If you zoom in a bit, you ...
0
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1answer
85 views

The sun's SOLAR WIND VS MAGNETAR

As we know magnetars have strong magnetic field but what if we swap earth with a magnetar and the sun will released a solar wind. Is the magnetar affected by the solar wind or not ?
3
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1answer
108 views

Where asteroids disappear

Scientists claim that objects left on the Moon can lie hundreds of years in the same condition like astronaut Charles Duke family photo. Why we don't see remains of asteroids inside or around craters? ...
38
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3answers
9k views

Does the Milky Way orbit around anything?

We know most of the objects in the Universe have a spherical or elliptical shape. The object which has less mass and gravitational pull orbits around the nearest object with more mass and ...
3
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1answer
291 views

Unable to locate Big Dipper through Polar Axis Finder

I have recently purchased a CG-4 Polar Axis Finder for my CG-4 mount. This PAF has markings on the lens for aligning with Big Dipper or Cassiopeia, which looks like this: I have aligned the PAF to ...
1
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0answers
32 views

Q: Calculating the luminosity of a galaxy

I am currently working on a project on which I am calculating the luminosity of galaxies by using the SDSS data. They use a system of asinh magnitudes, and according to their website they use a system ...
0
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2answers
83 views

How do you draw the ecliptic on a celestial sphere sketch?

I don't really understand how it's drawn on sketches of the celestial sphere. At first I thought it goes through east and west, but it does not. How do you know where to draw it? Example from Roy and ...
1
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1answer
43 views

Examples of absorption lines for main sequence stars

Where might I find a detailed table or figure containing the absorption lines and their corresponding wavelengths for each type of main sequence star? I'm trying to get the chemical abundance of ...
3
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0answers
32 views

Number of obscured AGN compared to unobscured AGN

Urry and Padovani 1995 proposed a unified model for Active Galactic Nuclei, which has since been recognised as a good model for AGN. If AGN are randomly oriented, then I'd expect there to be more ...
-2
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1answer
123 views

Wormholes man made are real? [closed]

Can we bend two points of spacetime in a way we would create a wormhole ?Why havent we tried it yet?How much energy would we need to do it?
5
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1answer
130 views

If the Mars polar caps were melted, how deep would the oceans be?

If the Martian polar ice caps melted, given a surface temperature and pressure that allow for liquid water, how large would the oceans be? Would they match their ancient glory, or would they be ...
2
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0answers
31 views

Eccentricity from Analemma

Can the eccentricity of a planet's orbit be found just from the analemma of its star? We can draw an analemma given the axial tilt and eccentricity, but how do we find the reverse? Note: I already ...
-5
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1answer
47 views

How does time dilation from a large body fall off? [closed]

A magnetic fields generally fall off as 1 / r^3 rather than 1 / r^2 for gravity. How does time dilation fall off from a large body? Where would the gravity and magnetic field line be in this chart ...
-5
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2answers
114 views

Can someone tell me what is exactly the curvature per mile in earth? [closed]

Earth is a planet as we all know.Astronomy examine the planets too.So whats the point looking for answers on other planets if you cannot give an answer to a simple question like the following. Basic ...
3
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1answer
88 views

Aphelion and the solstice

We have just passed one of the solstices and are approaching aphelion. The two events are close but not simultaneous. There is no very obvious (to me) reason why the two should coincide or be close. ...
3
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1answer
56 views

periodic inclination change circumbinary planet

I am studying circumbinary planets and I made a python model to calculate certain properties of the orbits, and when I calculate the inclination I get a sine wave. I do not see a way to predict the ...
-3
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1answer
165 views

What is the time dilation less a magnetic field?

Does time dilation drop off like a gravity or does resemble a magnetic field model? Could a smaller body with a magnetic field have more time dilation then a larger body without and to what degree?
2
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2answers
106 views

What would change if Venus rotated at a speed and direction similar to Earth?

I am interested in two aspects of this question. Imagine that Venus had a similar rotation speed and the same direction of rotation that we have here on Earth. What would change for Venus itself? I'm ...
3
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3answers
212 views

Why do scientists assume they can measure the shape of the universe if it is also widely believed to be infinite?

The shape of the universe is the question of whether the universe is flat, has a positive curvature or a negative one. More recently astronomers have compared radiation coming from extremely distant ...
0
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0answers
44 views

Why can you see both aurorae at the same time? [duplicate]

I wanted to know how it is possible to see both aurora borealis and aurora australis at the same time, since this video seems to suggest that it is possible. https://www.youtube.com/watch?v=...
0
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0answers
27 views

Galaxy-Galaxy Weak Gravitational lensing signal

I'm still new to gravitational lensing, and I've been trying to read a paper that has to do with calculating the week lensing signal of galaxy-galaxy interactions in a sample of galaxies. I understand ...
4
votes
1answer
254 views

Head on collision of two black holes [duplicate]

Inspired by If two black hole event horizons overlap (touch) can they ever separate again?, I was wondering what would happen if two black holes collided into each other in a head-on collision. In ...
4
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1answer
93 views

Observable universe equals its Schwarzschild radius (event horizon)?

The estimated age of the universe is 14 billion years. The estimated Schwarzschild radius (event horizon) of the observable universe is 14 billion light-years. What are the ramifications?
5
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2answers
113 views

If I could see from a Gravitational-Time dilated place to somewhere far which is not dilated, would I see fast moving people?

Gravitational time dilation like the one shown in the movie Interstellar, causes time to move slowly for someone within the high gravity reference frame. Now let's say that from such a place, I was ...
3
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3answers
117 views

What causes these asteroid trails to be so strangely shaped and repeated?

The Phys.org news item Hubble is the ultimate multitasker: Discovering asteroids while it's doing other observations includes the image below. What causes these asteroid trails to be so strangely ...
1
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1answer
55 views

How are “parallel fields” implemented on the Hubble Space Telescope?

The Phys.org news item Hubble is the ultimate multitasker: Discovering asteroids while it's doing other observations mentions the Hubble Space Telescope's use of parallel fields: A couple years ago,...
1
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0answers
65 views

Stars that don't fit $L=4\pi R^{2}\sigma T^{4}$?

When calculating luminosity/radius/temperature for several stars, I've noticed that while the majority of stars conform to the luminosity relationship $L=4\pi R^{2}\sigma T^{4}$, there are a few that ...
1
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0answers
42 views

How to calculate the distance to galaxies with standard candles?

I was wondering how the distance in Mpc could be calculated between Earth and a galaxy using the luminosity provided? Do not be shy to use all math necessary :)
11
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1answer
204 views

Are all satellites thought to be the result of collisions with the planets?

The leading hypothesis for how the Moon was formed was that another object collided with the Earth, throwing off a large lump of matter which formed into the moon. Is this thought to be the case with ...
5
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1answer
143 views

Can Eight Retrograde (seen from Earth) planets occur?

First of all, for the purposes of this question Pluto is a planet. So the eight planets being considered are Mercury, Venus, Mars, Jupter, Saturn, Uranus, Neptune and Pluto. My question is: can all ...
4
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1answer
64 views

Gravitational waves: how can scientists derrive the sizes and spin and distance of two merging black holes?

After recording the ripples of passing gravity waves I would imagine that some high-power math would be required to derive information about the sizes, spin, and distance of the merging black holes. ...
3
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1answer
104 views

How long does it take for an asteroid to get to Earth?

How long does it take an asteroid to get from the asteroid belt, to Earth? I know the asteroids don't go directly from the asteroid belt to Earth, but I know it's not quick, either. The time probably ...
1
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1answer
90 views

Why is this Einstein ring pink?

I'm having a hard time understanding this image in the CNN News item This glowing ring of light is from a distant galaxy. The caption (from this version of the article) says: This image shows ...
54
votes
2answers
11k views

If two black hole event horizons overlap (touch) can they ever separate again?

Hypothetical question based on my understanding that two event horizons that overlap (touch) can't ever separate again: Imagine a 1 billion solar mass black hole (so the event horizon is massive and ...
3
votes
2answers
122 views

Has the effect of other planets on Earth's orbit been ever measured?

Since other planets have their own gravitational pull, I'm wondering if their effect on Earth's orbit has ever been measured? I know that in comparison with the Sun's pull the effect might be rather ...
-1
votes
1answer
72 views

Higgs Field inside a White Dwarf

White dwarfs rank among the hottest things in the universe.In the early years of the life of the universe ,universe was very hot and the Higgs field was deactivated causing all the particles generated ...
3
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1answer
62 views

Brown Dwarf Cloud Models

There has been research that suggests that the changing brightness of Brown Dwarves are due to bands of Iron/Silicate clouds. Several models have been made that supports that hypothesis. My question ...
1
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0answers
16 views

Brown dwarf cloud models [duplicate]

There has been research that suggests that the changing brightness of Brown Dwarves are due to bands of Iron/Silicate clouds. Several models have been made that supports that hypothesis. My question ...
18
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1answer
2k views

Why did this meteor appear cyan?

A meteor recently flashed over Queenland. The meteor has been described by various people as appearing cyan or aqua, so the blueness of the image can't be due to a camera issue. The colour doesn't ...
3
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0answers
29 views

Small orbital body detection [closed]

What technology is required to detect a coconut-sized sphere in Earth orbit, at average altitude of communications satellites?
2
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1answer
77 views

What does cz mean?

Take DS Geminorum for example, it has a cz of -2.33 [2.96] My question is what does cz mean, what does is represent? and what does the value in the brackets mean? http://simbad.u-strasbg.fr/simbad/...

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