# Tag Info

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In case anyone can't follow the links. Here are the two pictures I mentioned. From: here and here. The first claims to show the track of the solar system barycentre in the heliocentric reference frame. The outer yellow circle marks the photosphere of the Sun. The second plot claims to show the track of the centre of the Sun in the barycentric reference ...

3

The technical name (in English) for the Sun is not Sol, which is just Latin for sun. The technical name for the Sun is the Sun. Another body in the sky has a similarly boring name, the Moon. There's one more boringly named object: in the Solar System: The Earth. Note the use of "the" (a definite article) and the use of capitalization to indicate a specific ...

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When I was very young, I didn't know that the sun in the sky was just another example of the stars I saw at night. I just wasn't surrounded by people who talked about such things. Later, when I learned that the sun was also a star, I was glad to know there was a star close enough to study. The term 'sun' was used to describe our star, even before people ...

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When language developed there was a need to refer to the "the bright shiny thing that makes the days light" and to the "sparkly things in the night sky". These things were very obviously different and so received different names. Several ancient greeks, and some renaissance Italians were executed for suggesting that the sun might be a star. And it wasn't ...

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The Earth moves in an elliptic orbit around the sun (or around the barycenter). If, in helocentric coordinates the Earth is at position (x,y), then in Geocentric coordinates the position of the sun is in position (-x,-y) So the locus of the Sun in Geocentric coordinates exactly matches the locus of the Earth in Heliocentric. The path of the sun in ...

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The effective temperature $T_\mathrm{eff}$ of a star, which is presumably what's been plotted, is defined through its relationship with the star's radius $R$ and luminosity $L$ by $$L=4\pi R^2\sigma T_\mathrm{eff}^4$$ This comes from the assumption that the star radiates like a black body at the photosphere. While this isn't strictly true, it's quite ...

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As Conrad Turner notes, that talk is about a device for blocking the light from another star (one you think might have planets orbiting around it). It's not for blocking the light of the Sun! If you try to look at a planet orbiting around another star, the glare from the star makes it very hard to see the planet. By placing a specially shaped device in ...

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A few responses to my own question: (a) TDB time isn't critical because it only varies from TT by a few milliseconds. (b) The resulting vector was not ECI but the vector from the earth to the sun in the celestial frame. I needed to build the celestial to terrestrial rotation matrix using iauC2t00a() (assuming zero polar motion since it's generally less ...

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The strength of the light from the Sun scales with the inverse square of distance [note 1]. That means that we would need to have the Earth-Moon system at $\frac{1}{\sqrt{2}}$ (approx 0.7) AU for the full Moon to be twice as bright [note 2]. Note 1: The fact that the Sun is not a point source of light has only a very minor effect on the scaling. Note 2: ...

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The term for when the sun is at its highest is "solar noon". https://en.wikipedia.org/wiki/Noon#Solar_noon It is the moment the sun crosses the meridian. The meridian is an imaginary half-circle that goes from the northernmost point on the horizon to the highest point directly above you and then to the southernmost point on the horizon. The sun is always at ...

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I live in an 'L' shaped building on the 14th floor, so I have a pretty clear view of the horizon. Up until March 20th of this year, the sun was setting behind the other wing of the building. My living room window faces roughly NW, and on March 21st, I was able to see the sun at the horizon for the first time this year. Each day, the sun will set a little ...

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