We're still digging through the thousands of comments and suggestions from the listener survey but we hear your requests and suggestions, and now you get to start reaping the benefits. Today we start our survey of the solar system with Mercury. What mysteries is it hiding from us? How similar is Mercury to the other rocky planets? How much do we really know about this first rock from the Sun?

<strong><a href="http://media.libsyn.com/media/astronomycast/AstroCast-070813.mp3">Episode 49: Mercury (15.3MB)</a></strong><br />&nbsp;<br />

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I really like this "tour of the solar system."

This is slightly off-topic, but I was surprised that there was never a mention of the Perseids on Astronomy Cast. ...A special reminder episode (remember Comet McNaught?) would have been very nice.

Seconded!

I'm also liking the updates on what you and Pamela have been posting on your blogs.

We just recorded Venus yesterday. Should we do the Earth or just skip to Mars?

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Fraser Cain
Publisher
Universe Today - Free space news delivered by email every weekday.

Please do Earth.

And how the moon ...or the lack of it would affect the way life evolved here.

Could it have without the satellite causing our seasons, and keeping us in a stable orbit?

also...

Without the moon... would we have had a denser atmosphere?

Just a small correction:
Actually, one year on Mercury is half a day long.

Number of days/year=number of rotation around its axis/year -1

The Earth rotates 366 times around its axis in 1 year : each day it rotates a little more than 360° to compensate for the advance on its orbits and it adds up to a full rotation in one year.

Likewise, the moon rotates once around its axis in its course around the earth, yet a "day" lasts forever.

So if in 2 years, mercury rotates 3 times around its axis, the day lasts 2 years.

Do Mars first. Then you can do Earth on the 52nd show. It'd make a fitting one year anniversary episode.

Naw, do Earth but do it from a perspective of a space probe and lander.

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Keeper of the Jabberwock

I'm thirding that you do Earth first, in the correct order of the planets. I'm anal about things like that. If you do Mars first and then do Earth, or skip Earth completely, I'll feel unsettled, and I know you guys do these podcasts each week just for my enjoyment. Also, are you going to include Pluto, even though it's been demoted as a planet? I've really been enjoying these podcasts and I've just made a donation. Keep up the awesome work.

Sorry, I know we're in a science-(not fiction)oriented forum.
But still, Mercury always reminds me of that mining venture of Lando Calrissian's on Nkllon


That fictional planet sounds a lot like Mercury:
very close to its star and rotating very slowly
(the slow rotation enables Lando to build a moving platform that always stays on the night side of the planet)

Two things I am wondering about in this context:
- how long does perceived daytime (or nighttime) last for an observer on Mercury?
- how fast would you have to move in order to stay on the night side?
(actually, you might have to move back and forth because of the weird effects of the 3:2 resonance, is that right?)

I really liked the mercury ep. I learn alot and I look forward to the jupiter planet.

I would think that Mercury being so close to the Sun that the Sun's gravity cause the center of Mercury to be molten enough to 'heal over' the craters and cracks?

I can't wrap my head around the physics of gravity assist. Why does travel in the same direction of another objects orbit speed something up while travel in the opposite direction slow it down? I keep thinking that the approach push and depart pull would cancel each other out either way and not change speed at all?

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"The only true wisdom is in knowing you know nothing." - Socrates

It has all to do with approach angle and departure angle. They are not the same.

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Keeper of the Jabberwock

hmmmm ... thanks jubjub - but how are the angles not the same??

Another thing, Pamela was explaining how the change in Mercury's orbit through time is also a result of the sun not being a sphere - what?? To what extent is the sun flat?

PS I've never seen this before: I typed in "dickey-goldberg correction" in my google bar and it only gave me one location on the entire internet!! and it was this episode 49!! Soooo - can anyone enlighten me on what that is as well?

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"The only true wisdom is in knowing you know nothing." - Socrates

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Probably the likes of:
R. H. Dicke and H. M. Goldberg, "Solar oblateness and general relativity"

(Google Scholar search for dicke goldberg)

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