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If the standard cratering chronology applies to Mercury, this shrinkage must have taken place during the last 4 billion years and not during the solar system’s early period of heavy bombardment.

Discovery scarp on mercury.

Large Scarp on Mercury. This long cliff structure crosses both flat lands and craters as it extends down the right hand side of this image.
This long cliff, nearly 1 kilometer high and more than 100 kilometers long, cuts across several craters. Astronomers conclude that the compression that made “wrinkles” like this in the plank’s surface must have taken place after the craters were formed. (credit: modification of work by NASA/JPL/Northwestern University)

The origin of mercury

The problem with understanding how Mercury formed is the reverse of the problem posed by the composition of the Moon. We have seen that, unlike the Moon, Mercury is composed mostly of metal. However, astronomers think that Mercury should have formed with roughly the same ratio of metal to silicate as that found on Earth or Venus. How did it lose so much of its rocky material?

The most probable explanation for Mercury’s silicate loss may be similar to the explanation for the Moon’s lack of a metal core. Mercury is likely to have experienced several giant impacts very early in its youth, and one or more of these may have torn away a fraction of its mantle and crust, leaving a body dominated by its iron core.

Today, astronomers recognize that the early solar system was a chaotic place, with the final stages of planet formation characterized by impacts of great violence. Some objects of planetary mass have been destroyed, whereas others could have fragmented and then re-formed, perhaps more than once. Both the Moon and Mercury, with their strange compositions, bear testimony to the catastrophes that must have characterized the solar system during its youth.

Key concepts and summary

Mercury is the nearest planet to the Sun and the fastest moving. Mercury is similar to the Moon in having a heavily cratered surface and no atmosphere, but it differs in having a very large metal core. Early in its evolution, it apparently lost part of its silicate mantle, probably due to one or more giant impacts. Long scarps on its surface testify to a global compression of Mercury’s crust during the past 4 billion years.

For further exploration

Articles

The Moon

Bakich, Michael. “Asia’s New Assault on the Moon.” Astronomy (August 2009): 50. The Japanese Selene and Chinese Chang’e 1 missions.

Beatty, J. “NASA Slams the Moon.” Sky&Telescope (February 2010): 28. The impact of the LCROSS mission on the Moon and what we learned from it.

Bell, T. “Warning: Dust Ahead.” Astronomy (March 2006): 46. What we know about lunar dust and the problems it can cause.

Dorminey, B. “Secrets beneath the Moon’s Surface.” Astronomy (March 2011): 24. A nice timeline of the Moon’s evolution and the story of how we are finding out more about its internal structure.

Jayawardhana, R. “Deconstructing the Moon.” Astronomy (September 1998): 40. An update on the giant impact hypothesis for forming the Moon.

Questions & Answers

what are wormholes?
facty Reply
Holes made by worms
Neil
What is the difference between black hole and white hole ?
Apsara
black hole is the place where the massive body makes a large disturbance in space time fabric causing large gravity even light can't escape from it and all the bodies enter into on reaching a specific distance.
SCIENCE
A white hole is a hypothetical region of spacetime and singularity which cannot be entered from the outside, although energy-matter and light can escape from it. In this sense, it is the reverse of a black hole, which can be entered only from the outside and from which energy-matter and light can
SCIENCE
White holes appear in the theory of eternal black holes
SCIENCE
worm holes join 2 distant region of spacetime through which you can travel, covering large distance in short time
Tanmay
for example if you need to travel from A to B on a plane of paper then you can travel in a straight line joining those points but a worm hole will join those points using 3rd dimention which will make you travel that distance in short time
Tanmay
Hi,Do you known Kyaw Nyein Chan Hein!
zin Reply
No
Astrophysicist
Hello : I'm Kyaw Nyein Chan
zin
Hi I'm Kyaw Nyein Chan
zin Reply
Hello : good moring, I'm Kyaw Nyein Chan
zin Reply
hello good morning
Astrophysicist
good morning bro
Tanmay
how do you do?
Astrophysicist
I am fine what about you?
Tanmay
same as you
Astrophysicist
cool
Tanmay
How the Big Bang is made .
Apsara Reply
Kyaw Nyein Chan
zin
What is heliocentric
Apsara Reply
helio is from the greek god helios or ilios and means sun. Centric is from central. So heliocentric means with the sun in the middle
Robin
Usually in the context of astronomy its about the moment the world goes from the idea of 'earth in the middle of the solar system' to the idea that the sun is in the center of the solar system
Robin
so from a geocentric (geo meaning earth) to a heliocentric idea
Robin
yes correct this theory states that sun is in the middle of the solar system rather than earth
Tanmay
oh you have already said this
Tanmay
Hello: good afternoon
zin
hello
Tanmay
Thankyou to all to solve my doubt . I don't know more about the solar system beacause i am a small little girl my old is 9 and i love science but i am trying to learn more about science .
Apsara
that's great you should definitely check science in a nutshell YouTube channel it will provide you with good information
Tanmay
that's great you should definitely check science in a nutshell YouTube channel it will provide you with good information
Tanmay
that's great you should definitely check science in a nutshell YouTube channel it will provide you with good information
Tanmay
here is the link ***youtube.com/c/inanutshell
Tanmay
You not alone Apsara I'm 14 but know little about the universe
Swazi
what is solar system
Himanshi
what do you mean by astronomy
Himanshi
astronomy is a study of planetary science.
Enceladus
Astronomy is a branch of Physics that deals with the study of celestial bodies.
Satyam
An astronomy is a scientist in the field of astronomy who focuses their studies on a specific questions or field outside the scope of Earth 🌍🌎🌏 . They observe astronomical objects such as star's , planets , moon , comets and galaxies - in either observational (by analyzing the data)
Apsara
what is the difference between astronomy and cosmology
Astrophysicist
The collection of eight planets and their moon's in orbit around the Sun , together with smaller bodies in the form of asteroids , meteoroids and comets . The planet of the solar system are ( in order of distance from the sun ) Mercury , Venues , Earth ,Mass , Jupiter , Sartune ,Uranus , Neptune .
Apsara
In Astronomy, we study about celestial objects but in cosmology we study the origin and the formation of universe.
Satyam
how much temperature were can find on neptune
Ayyan Reply
how can I apply online astronomy course ? if you have link send it.
Dawit Reply
what is astronomy
Khanyisa
Does any body know about Quantum Battery ?
Yabtsega Reply
yea I tell you briefly callme
Eyiba
How to get into the field of astronomy after completing B.tech in department of ECE?
Lakshmi Reply
Well my option is to do your job while getting a distant education from a reptued university for B.Sc and try for M.Sc in IIA and remaining astrophysics universities in india
Mahesh
Do I require GATE score for that?
Lakshmi
Yeah I meañ get a better score in gate.I think the university considers it and would help you to direct enroll into a masters progarmme
Mahesh
But the score should be good.
Mahesh
okay. I will do my best.
Lakshmi
Thank you
Lakshmi
hi guys I am from Ethiopia.I don't know detailedly about astronomy and I want to be astronaut .can you help me guys?
Dawit
I know that astronauts have to be physically fit
Tanmay
I don't know anything else though
Tanmay
If you want to be a astronaut you should complete medicine.
Mahesh
I had done by my b.tech ece long back and then I started doing job...but I still want to switch my field to astronomy, I m confused how shall I pursue it..
Shina
what should we pursue after 12th std B.Sc program and further or through engineering?
Ganesh
Maybe you should ask this question in quora.Professors will tell you answer to the question.
Mahesh
ok
Ganesh
Wanna join conversation about time travel?
Pratiksha Reply
Of course
Yabtsega
From where do we start?
Yabtsega
what do you think which year we would be able to time travel?
Tanmay
I think we can travel through a wormhole
Pratiksha
wormholes make you cover a distance faster than light can I don't think they can do anything with time though
Tanmay
hmm
Pratiksha
any guesses about which year that may be true?
Tanmay
time travel
Tanmay
but Morgan Freeman has told that time travel can be exist also through wormhole
Pratiksha
I think the past life
Pratiksha
I am dumb you are correct we can time travel with wormholes
Tanmay
yes you are correct
Tanmay
u see the episodes of Morgan Freeman on discovery channel, he explains nice and there also other astronomy people's which explain all about space time and all about universe
Pratiksha
no I don't watch discovery I will see it now thanks
Tanmay
yr welcome
Pratiksha
yr not dumb, every student are intelligent
Pratiksha
anything else interesting about space?
Pratiksha
I heard a really nice thought it said " We need time travel. When? It doesn't matter" What do you think of it?
Tanmay
sorry!!, but I didn't understand
Pratiksha
I don't know who made it but it's nice
Tanmay
I mean it takes 3 days and 14 hours for one revolution around its star
Hardik
it says that we need time travel but when do we need it? it actually doesn't matter because if time travel was made then we can go back in time and make it earlier
Tanmay
did you understand that thought? if yes, so can you explain me!
Pratiksha
so if say A makes time machine in 2080 then he can travel in 2010 and make that time machine again
Tanmay
I meant I don't know who made this
Tanmay
ohh
Pratiksha
still didn't understand 😅
Pratiksha
thought
Tanmay
I think my net is slow it is break ing up my
Tanmay
sentences
Tanmay
yeah!!
Pratiksha
it's fine
Pratiksha
I switched my internet it should be good now I meant that I don't know who made this thought does anyone know who made it?
Tanmay
@Pratiksha you understood it or should I simplify it more?
Tanmay
nahh!! I don't know, I heard it first time,
Pratiksha
just simply it
Pratiksha
@Hardik what do you mean? what is "it" here?
Tanmay
it means the π planet
Hardik
my last message didn't reach u ppl 😅
Hardik
simply if A developed time machine in the year 2080 then another person B can always use that time machine to go back in time and develope the same time machine in 2010 before the actual developer(A) developed that time machine
Tanmay
Hey Astros!
Info
@Hardik I your last message that says "I mean it takes 3 days and 14 hours for one revolution around its star" But this is also your first message
Tanmay
@Pratiksha it just says that the year of development of time machine can be changed easily and so will the developer
Tanmay
@Info hi anything to say here? any questions or answers or something
Tanmay
thanks tanmay patra
Pratiksha
welcome
Tanmay
is anyone interested to time travel!?!!!
Pratiksha
oh yes count me in
Tanmay
wow!! me too
Pratiksha
the study of astronomy is really very interesting
Pratiksha
a question for all of you. If you are told that you can either see the future of the earth or you can see the past of the earth then which one will you choose?
Tanmay
you can only see one thing no voting for both and also give reasons
Tanmay
I wanna past of the earth, because I want to make my future
Pratiksha
If you wanna past of earth for future then spend your present for that possibility
Mahesh
is there a competition formed by NASA in this month
Scientific Reply
nooo
Kygo
don't know
Pratiksha
It's because of presence of iron oxide in its surface.
Info Reply
That point is known as Singularity
Tushar Reply
Indian culture talks about black holes very well
Tushar
The word "MAHAKAAL" means black hole
Tushar
I love Quantum mechanics
Tushar
I love particle physics
Tushar
wow do you know about some maths in quantum physics?
Tanmay
Exactly.
Anti-Capitalism
Hi! Anybody can tell me that what is the exactly the black hole?
sach Reply
l no
Jee
OK then tell me
sach
A black hole is a space where gravity pulls so much that even light cannot get out.
Pratiksha
This can happen when a star is dying
Pratiksha
ok👍
Pratiksha
Explain more
sach
ok wait
Pratiksha
when a star of mass greater than 20 times the mass of sun dies it forms a stellar mass black hole
Tanmay
it bends space time so much that you need to travel faster than speed of light to get out of it
Tanmay
the innermost stable orbit of a black hole is that orbit where only light speed particles can orbit it
Tanmay
accretion disk of black holes are the matter that it gained from the surrounding orbiting the black holes
Tanmay
black hole forms when the center of very massive star collapsed it upon it self
Pratiksha
relativistic jets come out of black holes when the angle between accretion disk is not 90 degrees(this might be wrong but I know that it has to do something with magnetic field)
Tanmay
@pratiksha you took a lot of time to type this I thought you are Going to type an essay
Tanmay
@Gurjinder you can ask it here
Tanmay
sorry, but the text was not going 😅
Pratiksha
OK thanks
sach
yr most welcome sis
Pratiksha
I am a student class 12
Tanmay
there are 3 types of black holes stellar mass intermediate mass and super massive black holes
Tanmay
yeah!
Pratiksha
super massive black holes are found at the center of most galaxies
Tanmay
My hometown is at Odisha but I study and live in up
Tanmay
I still don't know a lot of stuff especially the maths involved in astrophysics
Tanmay
becoming an astrophysics thanks for your words
Tanmay
oh cool what all subjects are you studying
Tanmay
oh it happens sometimes
Tanmay
sadly chemistry XD
Tanmay
are there any chapters only for astrophysics
Tanmay
thank you same to you
Tanmay
oh that's a lot of hard work I hope you get great achievements can you tell me what all you are currently studying and which channel
Tanmay
oh that's a good strategy thank you
Tanmay
super
Jee
positional astronomy?
Tanmay
can you tell what positional astronomy is
Tanmay
I am fairly good in trigonometry but really bad at graphs
Tanmay
Hello everyone.Looks a cool discussion
Mahesh
ok I will practice thanks
Tanmay
where are you studying @Gurjinder
Mahesh
ok I will learn more
Jee
At which college I meañ.
Mahesh
Good
Mahesh
I want to be a astronomer,astrophysicist,theortical physicist and a engineer
Mahesh
I am not that good at self study
Mahesh
@Gurjinder that's a lot of hardwork I have high respect for you
Tanmay
I am always curious
Mahesh
nothing about astrophysics?
Tanmay
Lol
Mahesh
is college better than school?
Pratiksha
l am in school
Jee
Mainly from feymann if you want a good grip of basics
Mahesh
me too
Pratiksha
I just completed so what.Learning has no age limit.
Mahesh
which standard
Jee
at least your physics teacher should know something about astrophysics
Tanmay
l no
Jee
I love the book on quantum mechanics
Mahesh
though I hate classical mechanics
Mahesh
yeah the education system in India just cares about Mark's I don't know what will happen to the new system
Tanmay
yeah! yr right
Pratiksha
I love the new system.
Mahesh
They are going to introduce
Mahesh
but I am happy to know that people around the world are destroying it
Tanmay
the old system
Tanmay
Hmmm
Mahesh
what is black hole is something and what can do a black hole is another thing
Kygo
A black hole is a singularity where matter is condensed and a gravity well that light cannot escape from.
Micheal

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Source:  OpenStax, Astronomy. OpenStax CNX. Apr 12, 2017 Download for free at http://cnx.org/content/col11992/1.13
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