# Tag Info

8

Galileo was the first to observed the phases of Venus, also here, which he was able to do by his telescope, around 1610. It was the phases of Venus as well as observing Jupiter's moons orbiting Jupiter, that, to Galileo, confirmed without any question that Copernicus' model was the correct one and planets orbited the sun and moons orbited planets. Galileo'...

25

According to the caption for that picture on the same Wikipedia article, it is Francesco Fontana’s drawing of the supposed satellite(s) of Venus. Woodcuts from Fontana’s work (1646). The fringes of light around Venus are produced by optical effects.$^1$ Fontana lived from around 1580 to around 1656. He was an Italian lawyer at the University of Naples ...

16

Generally speaking, Venus is rarely a full disk, because it's inwards from the Earth's orbit, so it displays a full cycle of phases. Mostly, it looks like this: Image source Thus, it's not surprising that Fontana would depict it like that, since most of the time Venus appears partially full or as a crescent. Moreover, the only times when Venus appears ...

3

The sun rotates in anti-clockwise direction (when viewed from the north). The Sun, however, does not rotate as a whole body. It is made up of gaseous plasma and the time taken to complete one rotation increases with latitude. It takes around 25 days at equator and 38 days at poles (it is judged by the location of sun spots).

2

I may be wrong, but i think this may be related to orbital resonance effects. Due to orbital resonace, orbits are often destabilised and in some case stabilised as well. This inclination may have been produced over a long time, producing a more stable orbit(from the viewpoint of orbital resonance). For more info. See this https://en.wikipedia.org/wiki/...

7

Most asteroids are in an elliptical orbit around the Sun in the inner Solar System, i.e. a region comprising Mercury, Venus, Earth, Mars and the Asteroid Belt. What can happen is that an asteroid's elliptical orbit intersects a planet's orbit and this might gives rise to a collision. Most of times, when an asteroid gets too close to a planet, it has too ...

2

Juno probe's speed is in relation to what frame of reference? The escape speed of Jupiter is ~59.5 km/s and 150,000 kph ~ 67.1 km/s, so this speed must be in reference to the sun otherwise the spacecraft would not stay in orbit. Jupiter's orbital speed about the sun is ~13.1 km/s, which subtracted from the 67.1 km/s would result in ~54 km/s, thus more ...

1

Without seeing the particular example you have in mind it's impossible to be definitive, but without any context, for a probe in the Solar System, I'd assume heliocentric coordinates. Unless it's an orbital velocity around some other body, or an escape velocity from some other body, or of course if it's specifically stated to be in some other frame.

1

My advise on this question is to follow the data from the Juno spacecraft, which is now successfully in Jovian orbit. I suspect that a lot of phenomenology about Jupiter and related gas giants might be run through a paper shredder, and maybe a few will be supported. This spacecraft is tasked to address just this and related questions. I am no expert on ...

3

You are probably referring to a Carrington Event where a large coronal mass ejection from the sun hits the Earth and creates massive disturbances in the magnetic field, with the result that things like the power grid are damaged by the induced currents. On July 23, 2012 a "Carrington-class" Solar Superstorm (Solar flare, Coronal mass ejection, Solar ...

Top 50 recent answers are included