3
votes
1answer
253 views

How to calculate the heliocentric velocity of an object?

My task is to calculate the heliocentric velocity of an object to correct for wavelength in a spectrum. I have the RA, Dec and observation date, and I know that the NED velocity correction ...
1
vote
1answer
135 views

Is our Universe a hologram? [closed]

I watched a documentary where I heard some very strange theories that are difficult for me to comprehend. It is even difficult for me to explain what I heard. "Objects that fall into a black hole ...
3
votes
1answer
53 views

Gaia: What is the difference between CCDs used for astrometry, photometry, and spectroscopy?

My knowledge of CCDs is that these are sensors which collect photoelectrons. That's about it. What is a difference between CCDs used for astrometry, spectroscopy, and photometry? As an example, each ...
2
votes
1answer
135 views

Can we draw a min(distance) and max(mass) relation based on current observation data of nearby astronomical objects within several parcsecs?

The data precision now can exclude a >>$1M_{\odot}$ black hole, which has a , say 10000 year orbital period with our sun? We can draw a two dimensional diagram(Mass VS. distance) to show the region ...
4
votes
2answers
71 views

September 26 twelve hours sunrise to sunset?

I noticed in today's newspaper (Boston Globe, September 26) that sunrise and sunset were both at 6:25. That's the twelve hour day I'd have expected at the equinox. (Please retag if there's a better ...
3
votes
3answers
218 views

Less stars in the night, compared to 15-20 years back

I am not sure if my question is true or not. But this is what I observe regularly. When I was young and when I look at the sky, there were too many many stars were there. But now, from few months I'm ...
2
votes
1answer
161 views

Should a station in orbit around the Sun travel in the same or the opposite direction to the planets?

If we put a station in orbit around the Sun, and wanted to send transports as regularly as possible without the travel costs being prohibiting; should we have it rotate around the Sun clockwise, or ...
3
votes
1answer
179 views

Was there ever a Jupiter transit or Saturn transit?

I've watched the Venus transit 2004 with a small telescope, a relatively rare event, considering most people can only observe two in their life time. If E.T. were sitting in a sunny place on a moon ...
2
votes
1answer
78 views

Spheres in space [duplicate]

I know that gravity will turn a mass into a sphere, which is why planets and stars are that shape. But then we have asteroids and small moons which are not spherical. Such as a couple of Pluto's ...
5
votes
1answer
55 views

What visual artifacts are expected from the JWST?

What visual artifacts should we expect from the images that will be released from the James Webb Space Telescope? Specifically, do we expect 3-pronged diffraction spikes (any preview how they would ...
4
votes
2answers
102 views

Understanding Earth Tilt, Sun's Position and Lattitude Calculation

I've been trying to figure out how to calculate the latitude of my location with just the shadow of a stick cast by the sun. I am doing this under the assumption that I am stranded in some place with ...
3
votes
0answers
78 views

How does light so travel so fast?. [duplicate]

I've read that photon's have zero mass, hence no force is needed to accelerate them. But then the second question. How can gravity affect something which has 0 mass?. Yes, gravity(black hole) can bend ...
6
votes
1answer
145 views

Could an impact have resurfaced Venus 300 million years ago?

Venus surface isn't older than about 300 million years. The only explanation I've come across is that some kind of global volcanism resurfaced the planet. But couldn't it have been an impact event? A ...
3
votes
1answer
44 views

Stratospheric Balloon with an Xray camera

Some colleagues and I were planning to launch a stratospheric balloon in December. A thought occurred to me: what if we were to put some sort of xray camera in the payload? We are expecting a maximum ...
4
votes
1answer
111 views

What is the format of the data from the JPL's HORIZONS system?

I'm looking for accurate positions and velocities of the planets in the solar system over several decades. I want to simulate their trajectories using Newtonian laws of motion, and compare the ...
1
vote
0answers
40 views

LIfe without an ocean floor on an ocean planet?

Theoretically, wouldn't life need some sort of an ocean floor with irregularities where organic "soups" could "condense"? What about "membranes"? Don't theories suggest that if life came to be near ...
2
votes
1answer
22 views

Biosignatures for anaerobic or other early microbiology?

What are some possible atmospheric bio-signatures for a planet with anaerobic life? or even microorganisms before oxygen builds up in the atmosphere? Would there be a way of telling if methane, etc. ...
4
votes
1answer
229 views

When will Sirius be closest to the solar system?

Sirius is currently approaching the solar system, at a rate of 5.5 km/s, consequently in the future it will be closer and therefore brighter. When will Sirius pass closest to the solar system? How far ...
2
votes
1answer
83 views

Can we know where (South, East, West…) the moon will be at a specific time?

Apparently, a few nights from now (more specifically on the night between the 27th and 28th of September this year, nights being Belgian nights), we will have a lunar eclipse. That's great, and I ...
8
votes
2answers
811 views

What causes the antipodal bulge?

The Wikipedia article on tides shows a diagram with a tidal bulge both towards the Moon and on the antipodal point (the Sun isn't included in the diagram). Surely that's wrong - what would cause the ...
10
votes
2answers
257 views

Does any iron fuse in stars before they go supernova?

I understand that iron and all heavier elements consume more energy to produce than they make, and that is what eventually leads to a supernova. I also understand that a lot of the heavier elements ...
5
votes
3answers
156 views

How to scale down solar system data to simulatable values

Okay, I am seriously ashamed for asking this especialy when I geniualy study on physics but there is something that bugs me with the simulation I am working on. I am re-creating the solar system in ...
3
votes
1answer
70 views

Universal point for sky observation

Is there a place on Earth, where polar axis lies on the horizont and heaven equator is in zenit? If it exists, can I, in theory, see all the constelations available worldwide this night?
1
vote
1answer
56 views

Identification of Lunar mare (maria) from a taken picture

I'm in Brisbane right now. I took this picture 15 minutes ago from my balcony. Could you help me with identification of marked Lunar maria? I cannot compare any of these to this map. I think 1 is ...
2
votes
2answers
287 views

How Do we know about redshift?

Okay so scientists use the red shift to know that galaxies are moving away from us faster than light. How do we know that its not just red light from red stars. i mean most stars are in the infrared ...
1
vote
3answers
393 views

Where exactly does the Moon flip, given that it appears the other way up in the other hemisphere?

I've read in multiple sources that the Moon appears the other way up in Northern Hemisphere vs Southern Hemisphere. Here is one that explains why: Does the Moon look different in the northern and ...
1
vote
1answer
34 views

If we pumped an large EMP into High Earth orbit and it detinated would it act as a shield against solar radiation?

Could this pulse potentially shield spacecraft from harmful solar radiation. I was assuming an EMP would have little effect as a radiation shield because the pulse would not be rapid enough to ...
3
votes
2answers
76 views

Ocean floors on ocean planets?

I know that models of ocean planets typically have deep liquid water that transitions into exotic forms of ice. What I am wondering is if it makes sense to have an "ocean floor" composed of debris ...
4
votes
1answer
71 views

When is the belt of Orion slanted from right to left, going up? (Egypt)

I am trying to match up a detail of the Senemut ceiling to the time of the year it might involve. In the detail (shown below), the belt of Orion is slanted upwards from right to left: Notice that ...
8
votes
4answers
802 views

two black holes orbiting each other within their event horizon

Is there any argument against this situation: two black holes, one within the event horizon of the other, and the system is stable. It is interesting to me because that if this works, we could have ...
4
votes
1answer
177 views

What is the angle between the equator of the sun, and the plane of the Earth's orbit

I want to know the angle between the plane that passes through the centre of sun and is perpendicular to its spin axis, and the plane that contains the orbit of earth around sun? Is this a fixed ...
2
votes
2answers
181 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. ...
10
votes
4answers
2k views

How can we avoid needing a leap year/second?

Given the Earth's current speed around the sun and current rate & axis of rotation, what is the best way to keep time to avoid a leap year? How many hours should we have in the day and days in a ...
7
votes
2answers
123 views

Why you use log to measure metallicity in galaxies?

For example, I saw the next expression for matallicity in a paper: $\log(O/H) + 12$. I understand O/H is the O(Oxygen) to H(Hydrogen) ratio but why is there the number 12? And why the logarithm?
5
votes
0answers
60 views

The battle over Gliese 581 and Gliese 667C?

In 2014, Robertson et.al. made a case that stellar activity is masquerading as planets (here and here) for these well known systems. In both cases, they claim that the only real planets discovered so ...
4
votes
1answer
143 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?
5
votes
1answer
122 views

Is any consensus forming on the solution to the “Lithium Problem”?

The "Lithium Problem" relates to the fact very-low-metallicity stars appear to have a Li/H ratio approximately one third of what would be expected. The ratio should be the same as the prediction from ...
4
votes
3answers
204 views

If 50 tons or more of debris falls to earth everyday, is Earth getting heavier?

In turn, would that increase our gravitational pull?
3
votes
0answers
177 views

If two pieces of the same type of metal touch in outer space, they will bond together permanently? [closed]

Is this true? And if so, why? http://www.snapple.com/real-facts/cap-view/1003
1
vote
1answer
171 views

Calculate Dec and RA of a star from Euler angles and GPS data

I have 9DOF sensor (accelerometer, gyroscope, and magnetometer) that gives orientation via Euler angles (yaw, pitch, roll). Along with GPS data (latitude, longitude, elevation, time) this is passed to ...
0
votes
2answers
48 views

Conflicting information about the star Delta Pavonis?

Delta Pavonis has about the same mass as the sun so I would think that the evolutionary path would be about the same (the mass is given as O.991 M(Sun)/ not sure how we get this so accurately). It has ...
2
votes
0answers
70 views

EPIC 201367065?

I was extremely stoked when I read an article in January of this year that the Kepler2 mission found three Earth-sized objects (one possibly in the habitable zone) transiting a star only 150LY away. I ...
4
votes
1answer
105 views

How did pre-Earth's mass and orbit change at the Moon formation event?

The popular, but still disputable, Moon formation theory is that a pre-Earth was hit by a Mars sized planet. The mass ratio of Earth:Mars:Moon is roughly 100:10:1. Does this mean that pre-Earth was ...
1
vote
0answers
18 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
vote
1answer
30 views

Is Polar Lights observation possible at the latitude of 56° N?

Back in 2002, me and my friends observed a green glow in the sky at night in the form of giant slow moving spurts of flame, looking more dense near the horizon and more blurred at height. It was ...
0
votes
1answer
56 views

Correlation of planet sizes with star sizes?

I did my own amateur Kepler data analysis in May of this year of data from Kepler.nasa.gov/Mission/ discoveries. I found a strong correlation between star size and planet size (percentages). 37 of the ...
1
vote
0answers
39 views

Classification of Planets?

The data from Kepler has taught us that there is a much larger number of "Neptune-class" planets out there than we previously thought. I wonder, however, if this "dominance" of Neptunes is because of ...
2
votes
1answer
40 views

Reason for a correlation between Hot Jupiters and higher metallicity in Kepler data

This question is from an amateur data analysis I did in May of data from Kepler.nasa.gov/Mission/discoveries. There were 80 Jupiter size planets in the Kepler "confirmed" planet table on this website ...
2
votes
0answers
50 views

Unbelievably high masses/ densities in nasa website data

In May, I did my own amateur analysis of Kepler data that was supplied on Kepler.nasa.gov/Mission/discoveries. This was a table of all confirmed "Kepler planets" to date (April 1, 2015). This table ...
2
votes
1answer
77 views

The largest discrepancy in the history of science

I watched a cosmology lecture given by Leonard Susskind that convinced me to put my money on dark energy being a pressure caused by energy that is evenly distributed throughout the "vacuum" of space. ...

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