Understanding Mercury's orbit around the sun

[LKD]

I was watching the SOHO video of the suicidal comet, and I can not see to get a handle on what the orbit of Mercury is in 3 dimensions. http://sohodata.nascom.nasa.gov/cgi-bin ... ie_theater LASCO C3 3-11-10 through 3-13-10.

Looking at the video they offer, it seems like the planet is orbiting off the general plane of the solar system and we have a much faster orbit than the little planet does.

Is there someone who can explain it to me a little bit better, or more comprehensively?

Thank you of course.

 

[origin]

I was watching the SOHO video of the suicidal comet, and I can not see to get a handle on what the orbit of Mercury is in 3 dimensions. http://sohodata.nascom.nasa.gov/cgi-bin ... ie_theater LASCO C3 3-11-10 through 3-13-10.

Looking at the video they offer, it seems like the planet is orbiting off the general plane of the solar system and we have a much faster orbit than the little planet does.

Is there someone who can explain it to me a little bit better, or more comprehensively?

Thank you of course.

Mercury has an orbital inclination of 7 degrees second only to pluto - why the inclination, not sure maybe interactons between the sun and Venus?

Mercury has an orbital velocity of 172,000 km/hr and the earth has an orbital velocity of 107,000 km/hr. Mercury would have to be higher than earths orbital velocity or one of the orbits would not be stable.

 

[MeteorWayne]

Well, don't forget what the viewpont of SOHO is. It's about a million miles closer to the sun (out of 93 million) so it basically sees what we see.

Mercury has the most inclined orbit of any planet (7.0 degrees relative to the earth) so you are correct, it is tilted. That's one reason transits (When mercury passes across the face of the sun) are so rare.

There are software programs that allow you to see the 3D view.

One easily accessable tool is to use the jpl sbdb browser. I'll select an asteroid to get you to the starting point.

http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2 ... ;cad=0#orb

The handle on the right changes the tilt, you can bring it up to align it with the plane of the earth. Move it down and you get an overhead view. To see it move hit the >> arrow.

At the bottom is a handle for zoom (It's not the one right below the orbit diagram...it's further down and labeled Zoom)
so you can close in to just look at Mercury if you want.

 

[LKD]

Thank you both kindly.

That very much explains why when I initially saw the video, I was having a hard time understanding what it was I was looking at until there was a labeled image for me to reference.

Great link, Wayne, thanks.

I am always amazed at all these little odd programs that are freely accessible but if I ever tried to search for them through Google, I would have no hope of ever finding them.

Is there a place that offers a decent listing of good links?

 

[3488]

Actually third most inclined, KBO Eris (which is larger & more massive than Pluto) has a more inclined orbit than KBO Pluto.

Anyway, it appears that Mercury's inclined orbit is due to early interactions between the Sun, Venus & Earth.

At perihelion, Mercury is travelling at a heliocentric velocity of 56.6 kms (203,800 KPH), aphelion slows to 38.7 kms (139,300 KPH).

The SOHO LASCO observations showed Mercury passing through Superior Conjunction, i.e round the far side of the Sun.

Andrew Brown.

 

[MeteorWayne]

Ahh, but Eris and Pluto are Dwarf Planets, not Planets, which is why I phrased it the way I did

Among the 8 planets, it is the most inclined.

 

[LKD]

Haha. Good to know the ostracized 'dwarf' planets aren't ignored by all of us.

 

[origin]

Ahh, but Eris and Pluto are Dwarf Planets, not Planets, which is why I phrased it the way I did

Among the 8 planets, it is the most inclined.

I immediately notice the way you phrased your response, because I of course implied the that little pip-squeek Pluto was a planet - it is hard to teach us old dogs new tricks. :evil:

Although, I do have to say I think the new designations are a good idea. There was a very nice write up on that subject in Scientific American.

 

[3488]

Mercury Superior Conjuction. Sunday 14th March 2010 as seen from the SOHO spacecraft.

Mercury & the Sun were passing in front of Pisces, of which some of it's stars can be seen in the background.

LASCO C3.

LASCO C2.

Andrew Brown.

 

[LKD]

What is that bar that angle's off the blocked sun? Is that unavoidable hardware that takes away part of the image?

 

[3488]

It's the support of the occulting disk.

Andrew Brown.

 

[EarthlingX]

If you want a really nice representation of what looks like any orbit in 3D, see it for yourself in

Wiki : Celestia

Home : http://shatters.net/celestia/
Download : http://shatters.net/celestia/download.html

Recommended add-on page, after official - you can find more files on ESA and NASA usually on the respective mission pages :
Selden's List of Resources for Celestia

Missions with files, which i remember without much searching are Mars Express, Cassini, Messenger. I can check for direct file links, if anyone is interested.

Most of the space observatories have at least some basic orbital info, in other words, heavy traffic.

You can see some of Celestia images here, plus free software links, some might be a bit advanced, not images though :
SDC, SB&T : Virtual space tech

This applet is cool though, thanks MW for posting it probably the hmpfth-time :
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2 ... ;cad=0#orb

I will put it in (SDC - SB&T) Relativity Calculator.

Hm .. Which star catalogue is most up-to-date ? Similar interface ? ( please forgive me off-topicness)
Wiki : Star catalogue