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113 votes
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Why is it easier to escape the solar system than get to Mercury or the Sun?

Because the earth goes very fast around the sun. If you want to get to the sun, you need to slow down almost completely so that your speed relative to the sun becomes almost zero. If you don't slow ...
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54 votes
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Have any of the rovers ever recorded a solar eclipse on Mars?

No, because Mars can't have eclipses. Strictly speaking, Mars has only transits. The difference is that Mars's moons are smaller than the Sun as viewed from Mars, thus they don't block out the entire ...
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46 votes
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Do you need 0 km/s velocity to crash into the sun?

Wouldn't i inevitably spiral to sun surface even if i was faster than 0km/s ? No. On reasonable timescales, an orbit will have a fixed distance of closest approach, called "periapsis." (These ...
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36 votes
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What would happen if a satellite took a direct hit from a coronal mass ejection (CME)?

We can look at what happened when this actually occurred. The geomagnetic storm of March 1989 was caused by a Coronal Mass Ejection. Here are just a few of the many effects on satellites. One ...
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36 votes

Why is it easier to escape the solar system than get to Mercury or the Sun?

Changing orbits requires delta-v. To reach the Sun, you need to subtract delta-v such that your velocity relative to the Sun is near zero, which allows you to "fall straight down" into the ...
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33 votes

Has any object launched from Earth gone into the Sun?

No, not yet. The Parker Solar Probe became the closest ever artificial object to the sun on October 29th, 2018, surpassing Helios 2 which held the record since 1975 [1]. No other human-made object ...
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32 votes
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How to check, if there is currently an increased solar activity?

Looks pretty darned quiet to me right now: You can find that here, along with other measures of space weather. By the way, cosmic rays and solar activity are two entirely different things. Cosmic ...
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31 votes

What would happen if a satellite took a direct hit from a coronal mass ejection (CME)?

I spent a couple of years working in the Astrophysics and Space Physics Section of JPL. Working with the Space Physics folks taught me a lot about the solar wind and other space weather phenomena. ...
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31 votes

Is it really ~648.69 km/s delta-v to "land" on the surface of the Sun?

Addressing is the sun's mass and other quantities known well enough for this to be absolutely accurate? Well, the key to this is the vis-viva equation in your question. It's not actually important ...
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28 votes
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Is this really an image of the sun, or an "artist's conception"?

You can find the image on Flickr. On August 31, 2012 a long filament of solar material that had been hovering in the sun's atmosphere, the corona, erupted out into space at 4:36 p.m. EDT. The ...
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28 votes
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Why does the ISS need thermal blankets if the Sun is hot?

As noted in another question, the ISS faces some pretty hot temps. Remember, the Sun heats radiantly. When you're sitting in that much radiant heat, without an atmosphere to dissipate it, you're going ...
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25 votes
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Did any spacecraft ever use the Sun's gravity for acceleration?

It doesn't really work that way. We can use the Sun to change direction, but we need rocket thrust to increase speed with the msneuver. To begin with, the closest stars (apart from the Sun) are not ...
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24 votes
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Does NASA have spacecraft that are specifically made for orbiting around the Sun?

I suspect you mean objects that haven't left the solar system (and what is the boundary?) and that aren't orbiting another planet. Every object en route to another planet that has left the Earth's ...
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24 votes

Is it really ~648.69 km/s delta-v to "land" on the surface of the Sun?

The Vis-viva equation is $$ v = \sqrt{ GM \left(\frac{2}{r} - \frac{1}{a} \right) }, $$ The $GM$ product for the Sun is 1.327E+20 m^3/s^2. If 1 AU is 150E+09 meters, then when you are in a ...
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23 votes

Is oxygen present in the sun?

The sun is not "burning" in the sense you are used to: there is no chemical reaction going on. Instead, there is a very high pressure in the core of a star (like our sun) due to the high mass that ...
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23 votes
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Could we possibly see the shadow offset from Parker Solar probe on Earth?

The closer an object to the source of light, the larger the shadow it casts. That's true if we're talking about a point source or at least a compact source of light and "shadow" refers to ...
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23 votes

Did any spacecraft ever use the Sun's gravity for acceleration?

The "gravitational" (slingshot) maneuvers space probes are performing are actually not so much about gravity. The gravity is method to "tie" temporarily these two bodies, but you could (purely ...
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22 votes

Why is it easier to escape the solar system than get to Mercury or the Sun?

Escaping the solar system requires adding orbital velocity to the spacecraft. Similarly, getting closer in the solar system requires removing orbital velocity. It turns out Earth is more out of the ...
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19 votes

Do you need 0 km/s velocity to crash into the sun?

You need below 2866 m/s of orbital velocity at 1 AU to crash into the Sun. You technically don't need to slow down exactly to 0 m/s relative to the Sun in order to crash into it. Let's calculate the ...
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18 votes

Does NASA have spacecraft that are specifically made for orbiting around the Sun?

In addition to the definition given by David H, I would add Ulysses, which is specifically observing the sun from out of the plane of the ecliptic and might mean what the questioner is asking for. ...
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17 votes

Do you need 0 km/s velocity to crash into the sun?

And note that if you want to hit the sun the cheaper (but slow!) way to do it is to head out. 12.32km/sec will take you to infinity, at infinity a burn of 0m/sec will kill your orbital velocity and ...
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16 votes

Have any spacecraft been launched or proposed to make a survivable close encounter with the Sun?

Solar Probe, planned to launch in 2018, will get to within 8.5 solar radii of the Sun's surface. For comparison, Mercury gets no closer than 65 solar radii. Solar Probe will use a thick carbon-...
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14 votes
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Is it possible to reach the Sun without expending any fuel/reaction mass?

If you're already in a solar orbit, then yes. You can use a sail at an angle and send the reflections prograde. The result is to reduce your orbital energy and you spiral in. I recall it was a ...
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14 votes

Why is it easier to escape the solar system than get to Mercury or the Sun?

Based on the calculations presented by @uhoh I generated a plot showing the necessary delta-V for a fly-by mission, i.e. entering into a Hohmann transfer with a far point intersecting the orbit of a ...
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13 votes
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Speed of solar coronal mass ejection

The video is significantly sped up (videos of the Sun generally are sped up). CMEs move at an average speed closer to 500 km/s. That's why when we see the activity we generally have a warning of up to ...
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13 votes
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Which of the planets could we detect today from just the movements of the sun?

Getting hard numbers about how accurate measures we can get from current systems, adapted to the Sun instead of far away stars is difficult, bordering to impossible. But we can get data about the ...
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13 votes

A probe floating in Sun's surface

Thermodynamics says there's no such thing as a completely internal cooling system. The best you can do is pump heat to a cooler location. That's very difficult to come by in the photosphere. ...
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13 votes

Is this really an image of the sun, or an "artist's conception"?

I'm posting these images as a supplement @Hobbes's accepted answer and @TildalWave's comments (which includes links to these images). I started reading some of those links. The gallery is a good ...
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13 votes

Why does the ISS need thermal blankets if the Sun is hot?

Insulation can function in both ways, keeping heat on whichever side is desired. In space limiting the amount of thermal input from the sun is very valuable since that heat is easily acquired but hard ...
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13 votes

Did any spacecraft ever use the Sun's gravity for acceleration?

I think the question is based on a misconception about how gravity assists work. If you just let yourself get pulled to a distant object then continue out the other side, the same gravity that ...
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