Solar Definition and 1000 Threads

Homework Statement The Sun is lower in the sky during the winter than it is during the summer. How does this change affect the flux of sunlight hitting a given area on the surface of Earth? How does this change affect the weather? (I take it I'm supposed to consider the sun to have a...

Can anyone help me please? Are they all elliptic or just some? I need to know for planets, comets, moons and satellites All help greatly appreciated.

This is just a small part of one of my problems. I need to find the luminosity of a stellar population containing 100 solar mass stars and one 20 solar mass star. I think that the 20 solar mass star will dominate, but I am not sure. Here is the formula to use: L/Lsun = (M/Msun)^3.5 I...

We don't see matter rushing to a center point as though down a drain anywhere in the universe. Black holes' accumulation of matter must (except perhaps rare moments like a collision with another black hole) happen over a long period of time. Assuming a star, destined to be a black hole, began...

I'm having a little trouble understanding this, mainly the way the maths behind it works. I can't find any kind of derivation on the internet which is 'simple' and at a level I can understand. My understanding is that the photons from the Sun are absorbed by dust, so transferring momentum...

Homework Statement A flat and thin GaAs solar collector of 100 micrometer thickness is irradiated with 100mW of 650nm light (incident normal to the surface). The absorption coefficient is about 10^4 cm^-1 and the bandgap is 1.4 eV. Assume that the GaAs has ~100% internal quantum efficiency...

OK very crude first sketch let me try to explain and you tell me if it sounds remotely workeable. Likemany other eco nuts after the holy grail of energy, I'm trying to brainstorm a low cost solar CHP system. I'm of the opinion that passive solar is always going to win on a BTU/$ collected and...

Hi there, I am doing some research online trying to find a good site that explains to me how sensor resolution works. I have a very vague understanding right now and I was hoping someone could go through it with me. I'll give a bit of background as to the task I have. I have a 4 quadrant...

Why are solar systems and galaxies flat? I find it peculiar that astronomical clusters (ie: solar systems and galaxies) are arranged in a flat plane. Can someone explain why? I understand that: any solar system originates from a random cloud of dust and gas. This cloud will feel its mutual...

I have wondered lately about the amount of energy which interacts with the Earth's magnetic field. Further, to the extent not converted to light as with the auroras, what happens to it in the interaction? If the energy is significant, is it in any way absorbed, transferred or otherwise lead to...

Let us assume Ho = 71 1 / s In order for our solar system to stay in orbit around the milky way, the escape velocity must be greater than the recessional. Resc > Rrec (2GM / R)^1/2 > HoR Now let's refer to Kepler's third law to substitute in for the mass. T^2 = 4π^2R^3 / GM M = 4π^2R^3 /...

Consider a spacecraft attached to a sheet of material, a "sail," that absorbs sunlight. Assume that the sail is positioned to face the Sun and that the combined mass of the spacecraft and the sail is m. How large does the area of the sail have to be to propel the spacecraft away from the...

I am hoping to find how to determine the heat available from focused and concentrated sunlight. I am not confident in my math skills or understanding of some terms, so will describe what I want to do and how I expect to accomplish it. I mostly need an overview and some specific details or...

need help please hi all i need hulp on my project Im a senior electronic engineer student . my project is about heliostat skylight which use a mirror to reflect sun light to spacefic target. I'm going to use 8051 microcontroller to interface btween inputs which they are 4...

i am about to do a project on harnessing solar energy using fresnel lens. However, i do not understand how a fresnel lens works. Could someone please clarify how it works (how can it converge light despite having a flat face) and why does it have more converging ability than other lenses?

would we be able to see a total solar eclipse after about 600 million years from now?

i want to do a project on solar water purification. I just saw a video on purifying water using fresnel lens. However, i haven't found any information on how one can make a fresnel lens suited to the purpose. So, how does one make a fresnel lens?

Homework Statement Earth and Mars are both rocky planets, but Mars is half as far away again from the Sun as Earth, so radiation from the Sun is not as powerful at the surface of Mars as at the Earth’s surface. Using the values in Table 2, calculate the amount of solar radiation...

I am planning a solar collector system for domestic hot water and heating. I am attempting to calculate the heat loss in a storage tank. If we assume: Tank Volume = 1m^3 Tank Surface Area = 6m^2 Tank Contents = 1000L water Initial Water Temp = 90C (194F) The Temp Outside the Tank = 10C...

Can we say that Kepler in the early 17th century was the first person to know the distance from the Earth to all the known planets? One of his laws:The square of the orbital period is proportional to the cube of the radius(actually the semi-major axis). So he new Saturn was about 900 million...

Hello my friends, first I want to thank all of those who take their time to helping people like us. I have a question and is what is the most recent guide on making a very powerful Solar Cell, I am very interested in it, and the reason why I want to know this is for making more devices to cut...

My mom has a Texas Instruments TI-36 Solar calculator. A few days ago I found that there are functions for calculating combinations and permutations. The trouble is I can't seem to figure out how to use them.

Homework Statement A solar collector has an effective collecting area of 12 m^2. The collector is thermally insulated, and so conduction is negligible in comparison with radiation. On a cold but sunny winter's day the temperature outside is -20.0 C, and the Sun irradiates the collector with...

so I am testing out different designs on a nitrogen laser, and wanted a quick way to test whether or not one design had a more intense output than the other. without having to buy a sensor, my idea was to direct the beam onto a solar cell, then measure the output current. higher current wud mean...

I was wondering how long it takes to heat up materials. And how long will they hold their energy? Say for like thermal energy storage, how long does it take to heat up molten salts or other substances with sunlight? I guess I could just use Q=mcT and divide by time and then solve for time...

We are trying to build a solar water heater using a 4' x 10' trough design and are still trying to figure out how to rotate the trough so that it follows the daily sun East-West. We have a 12 volt car window motor and someone else has suggested we use a simple, 3.6 volt electric screwdriver...

Those of you living on the moon will see a rare sight tonight, a total solar eclipse. Not coincidentally, the entire US, and very little where else will see a total lunar eclipse. This will be one to tell your grandchildren about since there won't be another until June 15, 2011. Don't look...

Good day All, Just a quick question: The sun emits charge particles, very hot moving very fast, right? (stop if my knowledge is incorrect :smile:) What will happen if one can cool down and / or slow down said particles? TX

I am a 4th year Phy UG on a 5 yr plan and need some advice, these two courses overlap so I can't take both. I am interested in both topics but have more background in astrophysics, not much in the engineering area. I guess my indecision stems from a larger crisis I am having in trying to...

At time T(sunrise) the SHA = -81.361029147899785, which makes frac. hours to noon (SHA / 15.0). Is calculating the time of astronomical twilight to noon as simple as (SHA - 18) / 15.0?

Homework Statement trying to show that the units W m-2 are equivalent to kg s-3 Homework Equations 1 W = 1 J s-1 ? The Attempt at a Solution energy per unit time? p.s. I am very new to physics, a beginner in understanding the whole concept of units, any advice?

Hi, I am trying to create a program (3D simulator) that reproduces the Solar system's behaviour. In this idea, I am using Newton's first and second laws: F = G * m1 * m2 / ( r * r) a = F / m I already managed to create a stable system containing the Sun, Earth, Jupiter and other...

Hello. I was wondering about something the last few weeks and that is if the solar wind can affect communication systems between satellites. I am not referring to the physical damage that the solar wind might produce to the satellite, but the interference it might have on the radio signal that...

Greetings, I'm seeing programs that allow solar, wind and other types of power generation to be connected to your house (or business) and you are still connected to your grid. The power company meters both - what they provide to you and what your private generation provides. Your power...

School experiment: Shine lamp at a solar cell, and measure the voltage using a multimeter. Independent variable is the distance between the light bulb and solar cell, dependent variable is the voltage. What is the relationship between the two? And how exactly do I prove it? What I have...

I just noticed an item in Ned Wright's "News of the Universe" about a new determination of the solar system's speed. It is roughly what we've been saying, around 370 km/s in the direction of constellation Leo, but this paper determines it with increased precision...

Hi, I am a non physicist/astronomer and having a little difficulty navigating definitions. Apologies if the question has already been covered elsewhere. If I calculate the RA/ Dec of say, the sun, on a certain date and time, how do I find the lat/long of the point on the Earth's surface...

Why don't galaxies for giant "solar systems"?

Homework Statement (a) What is the minimum speed, relative to the Sun, necessary for a spacecraft to escape the solar system if it starts at the Earth's orbit? Homework Equations Kinetic Energy=Potential Energy 0.5mv^2=rGM/(r^2) 0.5v^2=GM/r Where M is the mass of the sun, and r is the...

what will be the difference if the solar panel will be directly connected to the 12 volt battery or the solar panel is connected to a switching regulator before connected to the battery..which is faster to charge?..and what will be the difference in terms of power transfer?

hello! Hope you all will be at quiet ease. I am looking for the guidance to observe the performance analysis of MPPT (Maximum power point Tracker) in parallel and series configuration with similar solar modules. I have two solar modules each having the following rating: - Maximum power...

Is our solar system either closer to or farther from other solar systems in our galaxy compared with the average distance of one solar system to another? Thanks, Jake

Hi..I joined this forum a couple of days ago and I find that this is the best place for newb like me to share and seek some ideas. I have a question to ask and I don't know if this had been asked before. Would it be possible to heat water to its boiling point by solar? The idea is to...

We have a model where we are to predict the temperature of the water outlet stream of a storage tank. Basically we have a solar heating collector that heats up a fluid which is present in a storage tank. The flow process is that the fluid flows through the pipes to the solar collector and back...

how can i obtain a thermophotovoltaic device to convert solar heat from a parabolic reflector to electricity? or is there any other better device that can convert heat directly to electricity?

First of all, if this should have went in the Engineering section, I'm sorry... I wasn't sure where to write this post. If a solar panel on Earth's surface can gather say 100W/m^2 in full sunlight, how much would the same solar panel be able to gather in space, outside of Earth's atmosphere...

hello, our team has a solar car project, and i am in charge of the solar array system. Now we have an average silicon solar cell of Voc 0.6 V and Isc 6 A, thus 3.5 W of power. We are given 6 sq. meter of area to cover with solar cells. This corresponds to around 2300 standard sized solar...

If a black hole is approaching towards our solar system, at what point could it be detected and is there anything we could do to avoid catastrophe? Would it make more sense to attempt to move the Earth in such a situation?

A letter in the current issue of Nature: ==quote== A two-solar-mass neutron star measured using Shapiro delay P. B. Demorest1, T. Pennucci2, S. M. Ransom1, M. S. E. Roberts3 & J. W. T. Hessels4,5 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, Virginia 22093, USA...

Everything is on the same plane, and I was wondering why. I mean like, if you laid a reallllly flat and thin plate out, then everything rotating around the sun would fall in that, I mean the planets, not comets or whatever.