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Questions regarding the closest star to Earth, at the centre of the Solar System.

1
vote
The cause of this phenomenon is the tilt of the Earth's axis. As the Earth revolves around the Sun, the tilt changes, the seasons progress, and more or less sunlight hits a given region of Earth, depe …
answered Oct 11 '14 by HDE 226868
2
votes
The effective sunspot number $R_{\text{eff}}$ is calculated through a mix of observations and model calculations. It focuses primarily on some parameter called the frequency of the ionosphere F2 layer …
answered Oct 19 '16 by HDE 226868
8
votes
Let me try to add some numbers to Steve's answer. The Sun's luminosity is about $L_{\odot}=4\times10^{26}\text{ J/s}$. Now, if we assume that the majority of that energy comes from nuclear fusion, we …
answered Jul 9 '18 by HDE 226868
6
votes
A page from the Institute for Advanced Study links to data from various modifications to the Standard Solar Model. The newest given there is from Bahcall1 et al. (2005), which I'll use as an example. …
answered Aug 3 '16 by HDE 226868
6
votes
From theory It is possible to numerically integrate the equations of stellar structure over time to figure out how a star will evolve. Some basic informed "guesses" about the central and surface prop …
answered Mar 28 '17 by HDE 226868
7
votes
The answer to your first question has to do with luminosity. It's a measure of power, the energy given off by an object in a certain amount of time, which you can think of as brightness. The more lumi …
answered Nov 26 '16 by HDE 226868
19
votes
During a sunset, the Sun is lower in the sky than during most of the day - much lower. Therefore, light from the Sun travels through about 120 miles of dense atmosphere, compared to the roughly 2 mile …
answered Aug 21 '17 by HDE 226868
3
votes
I'm getting a slightly different figure from space.com (not my favorite source, but a source nonetheless), which says The core extends from the sun's center to about a quarter of the way to its su …
answered Oct 22 '14 by HDE 226868
17
votes
Here's my answer. I'll try to make it as comprehensive as possible. It's pretty hard to define the edge of the Solar System. Most people would probably define it as where objects are no longer gravit …
answered Oct 4 '14 by HDE 226868
16
votes
It is true that a surprisingly large number of stars are smaller (and thus less massive) than the Sun. However, the stars that are bigger than the Sun are often much bigger. Look at this chart: Im …
answered Jan 9 '16 by HDE 226868
2
votes
Names of stars can serve a variety of purposes. Let's look at the different names and designations of Betelgeuse, for example. A star's colloquial name, for lack of a better word, is sometimes chose …
answered Jul 17 '18 by HDE 226868
8
votes
Picture the Earth as a small ball suspended in midair, not moving, although it's rotating on its axis. Unless forces are applied to it, absolutely nothing will happen. That's conservation of energy (o …
answered Jan 2 '15 by HDE 226868
6
votes
When we look at spectral lines in a star's spectrum, we're actually looking for absorption lines, not emission lines. A star's spectrum usually resembles that of a black body, continuous and smooth. H …
answered Oct 19 '17 by HDE 226868
2
votes
This is a variant of pi, or "pomega". In LaTeX, you can get it by using \varpi $$\varpi$$ TeX has a question on the 'var' prefix, and Wikibooks has somet …
answered Jun 20 '15 by HDE 226868
2
votes
Normally, the two main sources of cosmic rays are considered to be the Sun (solar energetic particles) and galactic or extragalactic sources, although extragalactic sources are more common. Surprising …
answered Oct 26 '16 by HDE 226868

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