# All Questions

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### How can I download all of this JPL MRO imaging data at once?

There are several files. I think that they all needs to downloaded to have the complete dataset. Is there a particularly good way to download them all in one shot? https://pds-imaging.jpl.nasa.gov/...
23 views

### The colour of blue dwarf stars

The paper "M dwarfs: planet formation and long term evolution" describes blue dwarf stars, a hypothetical next-stage in the lifespan of red dwarf stars within a certain mass range, after which they ...
22 views

### Ecliptic line plot in a map

Is there any url that can give me data of ecliptic line that i can plot in a map. i.e i need earth's latitude and earth's longitude of ecliptic line for a specific time and date. Right now i only ...
19 views

### How much of a molecular could can end up as “starstuff”?

Stars form within molecular clouds. These clouds can be up to 6 millions solar masses. When the cloud collapses into stars, is it possible to know a rough figure for how much of this material actually ...
17 views

### Lifespan of B-type subdwarfs

According to the Extrasolar Planets Encyclopedia, the B-subdwarf Kepler-70 lost its helium envelope and became a blue-white subdwarf roughly 18.4 million years ago. (sources: archived encyclopedia ...
21 views

### Binocular highlights from Tasmania next few weeks?

My friends are visiting southern Australia and Tasmania for the next few weeks. I am lobbying them to bring my Nikon 8x42 binoculars so they can appreciate the Milky Way and possibly see a few other ...
31 views

### Is it possible to build a ground-based telescope that can directly image Earth-like planets orbiting in the habitable zone of sunlike stars?

In the following discussion I will refer to Earth-like exoplanets planets orbiting in the habitable zone of sunlike stars simply as “Earth-like exoplanets." NASA is currently developing or ...
16 views

### What was the distribution of the elements and compounds in the protosolar nebula?

I've been reading some articles on planetary formation in which it is mentioned that the composition of the protoplanetary disk changes depending on the distance to the protostar. At great distances ...
13 views

### Is the turn-off point of the main sequence the same as the terminal-age main sequence?

The turn-off (TO) point is one tipping point on the Hertzsprung-Russell diagram (HRD) where low-mass stars start to evolve from the main sequence (MS) toward lower temperatures. If I understand it ...
20 views

### What makes some meteor showers continue for days, while the “Unicorn shower” can be shorter than one hour?

The Washington Post's One hundred meteors in 15 minutes? ‘Short-lived outburst’ of shooting stars forecast for Thursday night. says: A “short-lived outburst” is forecast for Thursday evening around ...
30 views

### When is the best time to observe M81 from the Northern Hemisphere?

I have read that the best time to view M81 is during the spring. Considering its RA is ~10h and Dec. is +69°, wouldn't February 21st be the best time to view it since this is about when it transits my ...
18 views

### Freefall timescale for a Jeans-unstable hydrogen cloud of mass M

I'm working on a project (personal, not academic) that involves calculating the collapse timescales for protostars which will end up becoming stars of varying given masses. I'm treating the pre-main ...
49 views

### How long for the sun to traverse its diameter at the pole?

As the sun rises once per year at the north/south pole, the time taken to rise (and set) must also take significantly more time to complete to rise (and set). How long does this take at either pole? ...
19 views

### Determining Horizontal Coordinate System data (azimuth, altitude) for geographic locations

I would like to determine, specifically, azimuth and elevation data for any given location on the surface of the earth relative to another location on the surface of the earth (for my purposes, the ...
53 views

### Black hole collision animation: What are these extrusions?

In this video uploaded by LIGO Lab Caltech, two inspiraling black holes are depicted. The video's description explains what is shown and can be summarized by: The colored surface is the space of ...
45 views

### What is the least dense exoplanet?

An exoplanet with density 0.31 grams per cubic centimeter has been found. Is this the least dense exoplanet we know of?
53 views

### How was lunar eclipse proven using the scientific method? [on hold]

I read a few articles about lunar eclipses and while they explain the science behind them, they do not describe who explained it and how it was explained using the scientific method. Some of them ...
10 views

### Creating a 2D matrix from 2 FITS images of unequal dimensions for Radio/FIR correlation

I have two images of NGC 6946: ...
61 views

### Ecliptic line data

I would like to get the data of ecliptic line with respect to celestial equator for a particular day. Is there any specific URL that can give me this. I only have data for declination of Sun and the ...
501 views

### Ross 128 (What does the number mean?)

I see that there are a number of stars that have a number at the end of them. Ross 128 is an example. What does this number mean?
73 views

### Hot Jupiters around heavy stars?

Hot Jupiters are giant planets that are very close to their host star. How many Hot Jupiter exoplanets have been found around stars more massive than our Sun? Has the number of Hot Jupiters ...
117 views

### Are there only a set number of atoms in this universe?

As per the title, are there only a set number of atoms in the universe? Or does the universe make more atoms, and if so, how does it work? I'm a high school student that just had a question during ...
9k views

### Is Earth's Surface “In orbit”?

I'm having trouble understanding relative angular/tangential speeds at increasing altitudes above Earth's surface. In particular, I find this comparison of tangential velocities on Wikipedia very ...
98 views

### How can a star be “thrown out of the Milky Way” by Sagittarius A*?

A recent publication reports that a hypervelocity star on course to leave the galaxy was found, likely accelerated by the black hole at the center of the Milky Way in a process predicted by Jack G. ...
32 views

### How to calculate the Subsolar's Latitude and Longitude for a given Date and Time from RA and Declination? [on hold]

I think that the latitude is equal to the declination. How to calculate the longitude from the RA?
68 views

### How much starlight do black holes absorb?

Can it be calculated how much light from other stars a black hole of certain sizes would absorb? And how long will it take for the number of active stars to decrease to the point where Hawking ...
22 views

### Could we detect an extraterrestrial signal with the SKA radio telescope?

As I have not seen this question answered and, following the rules: https://stackoverflow.blog/2011/07/01/its-ok-to-ask-and-answer-your-own-questions/ , I would like to answer this important question. ...
75 views

### how is it possible to see the sun and the moon at the same time? [duplicate]

I once saw the sun and the moon at the same time once. How is this possible? Im from london england U.K and this probably some time in 2017 autumn time at around 6pm any Ideas.
76 views

### How to determine the orbital period of an asteroid using Kepler laws given its orbit's radius?

Given that the mean distance of an asteroid from the Sun is $450 \times 10^6$ km is it possible that the asteroid completes one rotation around the Sun in two years? According to the third law of ...
2k views

### What are the minimum element requirements for a star?

What elements would be essential for a star to exist? From what I understand our sun is made of mostly hydrogen and helium and most stars have small amounts of heavier elements like carbon, nitrogen,...
224 views

### If a star were travelling at 99% of the speed of light, directly at Earth would we see it?

Stars being flung from black holes in the news made me question if something were heading directly for us at the speed of light, would we even know? Update: Since it's impossible for a star to travel ...
55 views

### What exactly is the relationship between the orbits of Neptune's moons Naiad and Thalassa?

Scitechdaily's Wild Orbits of Neptune Moons a ‘Dance of Avoidance’ [Video] links to the YouTube video Neptune Moon Dance (Naiad and Thalassa) and says: In this perpetual choreography, Naiad swirls ...
82 views

### Earth's magnetic field vs. refrigerator magnet

According to this article: The Earth's field ranges between approximately 25,000 and 65,000 nT (0.25–0.65 G). By comparison, a strong refrigerator magnet has a field of about 10,000,000 ...
23 views

### Does The ISW Effect Predict Net Redshift Over Distance?

The Integrated Sachs–Wolfe (ISW) effect is concerned primarily with the study of the Cosmic Background Microwave Radiation (CMBR), but seems to demonstrate that photons passing through voids suffer a ...
47 views

### What will happen to a object if it somehow crosses universal speed limit? [closed]

Speed of light, ( 299792458 m/s ) is considered to be the universal speed limit. Let us hypothesize that we found an object with the ability to go beyond light. So what are the things that the object ...
38 views

### Why is earth a giant magnet? [closed]

If it is a giant magnet then will it produce a flow of electrons due to the magnetic flux effect or not?
331 views

### Are the orbits of all triple star systems at least technically unstable?

Background: In the Circular Restricted Three Body Problem (CR3BP, CRTBP) some halo orbits are mathematically stable. That means that the orbit of the third body is closed, periodic, and stable ...
5k views

### Why are there so many binary systems?

Most star systems are binary, but why is that? Why would new stars form close to others, and not (relatively) evenly spread? And even if they are clustered close together, why are the majority binary? ...
103 views

### When do radio and tv signals become indistinguishable from background noise of the universe?

I understand the rate an EM signal broadcast uniformly from the Earth will decrease in its power is governed by the inverse square law. How far from Earth will radio and tv signals become ...
109 views

### Hills' mechanism for making Hypervelocity Stars

In Hill’s mechanism, the gravitational tidal force of a single MBH disrupts an approaching binary. One star is captured on an eccentric orbit around the MBH and, by conservation of energy, the ...
19 views

### How to determine Az-El pointing of a telescope spiral scan?

I am writing a simulation of an automated telescope observation program. One part of this is to run a spiral scan pattern on and around objects of interest. I would like to tile this scan pattern so ...
86 views

### If we've only observed Oumuamua as a single pixel, how can we know its shape?

On a separate Oumuamua question (Oumuamua alien space junk?), I was confused how shape could be inferred from a single pixel, per another user's (@Uwe) comment. It was suggested I ask this question ...
45 views

### Beneficial astronomical uses of satellite constellations like Starlink?

Has any thought been given to software that would use predictable occultations by Earth-orbiting satellites to improve (rather than degrade) astronomical observations? Potential challenges I could ...
88 views

### Will the conditions that allow life to evolve still be around in a trillion years?

Some billions of years ago, systems like the Earth couldn't emerge and therefore life couldn't arise, because not enough of the heavy elements had formed yet. Assuming there'll neither be a big ...
21 views

### How to estimate the uncertainty of the average velocity of a galaxy given the uncertainty of its flux?

I am doing an experiment about the Tully-Fisher relation. I found the Flux density of the galaxy for different velocities, using DS9. I estimated the uncertainty in the flux due to the background ...
62 views

### Could S5-HVS1 conceivably still hold on to any planets?

If the star (S5-HVS1) has been accelerated to 1,700 km/s by a close encounter with the super massive black hole at the centre of our galaxy (Sagittarius A*) what would happen to any planets orbiting ...
111 views

### Is the sun flipped on the other side of the world?

As the orientation of the moon is different in the northern and the southern hemisphere, is the orientation of the sun different in both hemisphere? Does a sunspot appearing in the Sun northern ...
25 views

### who use the GADGET-2 pack for simulation? can I do it with my PC?

I want to do hydrodynamic simulatin for universe at vary redshifts. How can I do it? or how can I find an simulation of universe for use my work?