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6 views

line of lights across sky

This morning at 6AM I saw a line of lights coming out of Orion, moving across the North star then Big Dipper and disappearing into the early dawn. I saw at least 30, no idea how many came before I ...
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1answer
12 views

What do you call it when a satellite goes once around its planet?

When a planet or a satellite turns around itself, its called a rotation. When a planet goes once around the Sun, it's called a revolution. What do you call it when a satellite goes once around its ...
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2answers
26 views

What makes the planets to be symmetric

I have seen, in my text books, and on nasa sites, the all the planets are symmetrical. And universe also love symmetry. What cause this symmetry, why the symmetry is important. As we know that ...
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1answer
11 views

Calculating object velocity at perihelion

I would like to calculate the velocity of an asteroid orbiting around a star (Sun) at the perihelion of its orbit. I know the excentricity of the ellipse and its semimajor axis. I have found that the ...
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2answers
29 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 ...
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1answer
9 views

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/...
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0answers
26 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 ...
2
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1answer
23 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 ...
14
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3answers
1k views

Which stars did the Sun form with?

The Sun formed 4.5 billion years ago, in a molecular cloud. I assume that there were other stars in the vicinity (as is common in molecular clouds). Which stars are they? Where are they now? Are they ...
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3answers
169 views

How do I get started in astronomy data analysis?

I am learning some machine learning (I have previous background in statistics) on my own, and I am interested in getting some hands-on practice by doing some ML analysis in R and Python. Given how ...
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1answer
24 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 ...
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0answers
34 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 ...
2
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1answer
145 views

Based off of the study that found the universe has a positive curvature, how big would the whole universe be?

This study found that the universe has a positive curvature https://www.nature.com/articles/s41550-019-0906-9. I didn't really want to buy it and see if it says how big the universe might be. I know ...
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5answers
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,...
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1answer
34 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 ...
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4answers
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 ...
4
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1answer
95 views

What is the LSST's plan to address frequent satellite trails in data?

update: From Nature.com News article: SpaceX launch highlights threat to astronomy from ‘megaconstellations’: But an upcoming, cutting-edge telescope could be in bigger trouble. The US Large ...
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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 ...
6
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1answer
1k views

If an Asteroid was to strike the Earth, would it affect the Earth's rotation?

If an Asteroid was to strike the Earth, would it affect noticeably the Earth's rotation, and if so, how large would this Asteroid have to be?
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2answers
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?
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0answers
32 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 ...
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0answers
17 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 ...
2
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1answer
34 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 ...
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2answers
424 views

If a comet strikes a glacier, does it make a print on the land below?

The Younger Dryas Impact Theory describes an asteroid impact in Northern America, possibly the eastern part of Hudson Bay, which contributed to the end of the last ice age. If a comet strikes a ...
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0answers
107 views

The recent results on Hubble constant measurements

In recent news there is this announcement In the introduction they say: Distance measurement discrepancy: a $4.4σ$ tension on the value of $H_0$ and I understand the discrepancy is with the ...
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1answer
79 views

The energy density of DM (to be fluid,state parameter=-2)increases with time. Does it violate the concept of accelerating universe?

We know that dark energy with value of state parameter $\omega<-1$ is called phantom dark energy model. In this model if we assume dark energy to be a fluid with value of state parameter $\omega=-2$...
3
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1answer
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? ...
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0answers
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 ...
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2answers
77 views

Could different views of the universe simply be different points in time?

I'm not sure if this is the correct stackexchange site for this question. I've been reading this article on Vice Motherboard There’s Growing Evidence That the Universe Is Connected by Giant ...
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1answer
20 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 ...
8
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2answers
164 views

Could a star closely orbit a black hole long enough for the star to have lost 0.5B+ years to time dilation?

I was wondering how stable a close star-black hole system could plausibly be, and thus how much time a star could plausibly miss out on (from an outside observer's perspective) due to being in an ...
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2answers
228 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 ...
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1answer
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?
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0answers
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 ...
4
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1answer
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 ...
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0answers
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 ...
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0answers
11 views

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

I have two images of NGC 6946: ...
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1answer
99 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. ...
2
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1answer
74 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 ...
3
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2answers
95 views

Electron Degeneracy Pressure

The Z/A term for calculations of degeneracy pressure for white dwarfs is given as 0.5. But I can't find an explanation as to why. For my assignment, I am trying to find the degeneracy pressure for the ...
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0answers
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 ...
3
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1answer
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 ...
4
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3answers
2k views

Could the earth become a star if more mass was added?

I've heard that the only difference between a star and a planet is mass, meaning that if planets accredited enough mass they would too become stars. Does this mean that the star started off as a ...
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0answers
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?
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3answers
266 views

Struggling to understand the phases of the moon

Source Typically this diagram is how the phases of the moon are explained but the issue is this, namely, the phases seen on the right half are not possible. All the phases should appear on the left ...
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4answers
1k views

Can satellites travel in clusters?

Last night we saw a large cluster of what looked like exceptionally bright stars that moved, as a group, across the night sky in Lancaster, PA. It was about 9:15 pm, and they moved roughly from SW to ...
2
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1answer
73 views

How spectrographs that measure radial velocities manage to translate variations in the stars' spectrum lines into the “speed” of the star?

Like ESPRESSO or CARMENES, for example. I just don't understand the process or the way these spectrographs manage to obtain the velocity of the "wobble" of the star (due to the presence of another ...
2
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2answers
77 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 ...
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1answer
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 ...
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0answers
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. ...

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