Skip to comments.Astronomy Picture of the Day -- MESSENGER's First Day
Posted on 10/08/2011 8:06:16 AM PDT by SunkenCiv
Explanation: One solar day on a planet is the length of time from noon to noon. A solar day lasts 24 hours on planet Earth. On Mercury a solar day is about 176 Earth days long. And during its first Mercury solar day in orbit the MESSENGER spacecraft has imaged nearly the entire surface of the innermost planet to generate a global monochrome map at 250 meters per pixel resolution and a 1 kilometer per pixel resolution color map. Examples of the maps, mosaics constructed from thousands of images made under uniform lighting conditions, are shown (monochrome at left), both centered along the planet's 75 degrees East longitude meridian. The MESSENGER spacecraft's second Mercury solar day will likely include more high resolution targeted observations of the planet's surface features. (Editor's note: Due to Mercury's 3:2 spin-orbit resonance, a Mercury solar day is 2 Mercury years long.)
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Nice pictures though it seems like such a waste of resources since man would be incinerated if he attempted to make a landing there.
Still I have to give credit to NASA for a great picture.
Bush’s fault. That’s what happens when you don’t re-elect Obama and give the planet a chance to heal.....
>>Nice pictures though it seems like such a waste of resources since man would be incinerated if he attempted to make a landing there.
Well, not really, if he landed on the back side he’d be frozen to death.
COULD YOU IMAGINE THE SUNRISE ON MERCURY THOUGH?
Thanks, SunkenCiv, for all your postings, which provide us with nuggets of goodness amidst the political gloom.
Right...so imagine the only ‘reasonably habitable’ temps would be a narrow band, running roughly north-south, where space zero meets sun melt...
I’ve always wondered what that’s like.
Looks like the Moon, which is probably why this pic makes it look like Mercury’s mooning us.
Silly, they’ll go at night.
The day is 176 Earth days long, so, plenty of time to explore the night-side surface, given the probable length of the mission. Mercury’s one of the handful of Solar System destinations possible for human landfall.
Of course, the night-side surface will be explored by starlight. There’s no twilight, because Mercury’s got very little atmosphere, despite its density.
My pleasure, and thanks for the kind remarks.
Mercury is tidally locked but there is some sun movement in the sky due to its somewhat elliptical orbit. As I understand it, near the terminator between day and night there are 3 sunrises and 3 sunsets per mercurian day for some reason.
Thanks JPB! Nice link, btw.
Thanks for the MLB thread link!
I’m going to start a new thread for the ALCS and NLCS playoffs this afternoon and will post the link in my tagline for that too.
I was wrong about it being tidally locked but its got an odd orbit to axis rotation ratio. 3 days take 2 mercurian years.
“Mercurys axial tilt is almost zero, with the best measured value as low as 0.027 degrees. This is significantly smaller than that of Jupiter, which has the second smallest axial tilt of all planets at 3.1 degrees. This means that to an observer at Mercurys poles, the center of the Sun never rises more than 2.1 arcminutes above the horizon.
At certain points on Mercurys surface, an observer would be able to see the Sun rise about halfway, then reverse and set before rising again, all within the same Mercurian day. This is because approximately four days before perihelion, Mercurys angular orbital velocity exactly equals its angular rotational velocity so that the Suns apparent motion ceases; at perihelion, Mercurys angular orbital velocity then exceeds the angular rotational velocity. Thus, the Sun appears to move in a retrograde direction. Four days after perihelion, the Suns normal apparent motion resumes at these points.”
Well, not really, if he landed on the back side hed be frozen to death.
Are there areas where the porridge is just right?