The document discusses several topics related to planetary formation and astronomy. It describes the proto-planet hypothesis which proposes that proto-planets formed from solar nebulae and broke into smaller concentrations. It also discusses the giant impact theory of lunar formation, which is currently the most widely accepted explanation that the Moon formed from a collision between Earth and a Mars-sized object. Additionally, it provides overviews of the Big Bang theory, cosmic microwave background radiation, redshift, black holes, and Kepler's laws of planetary motion.

1. Proto-planet hypothesis of Kuiper
Proto-planets is the disc containing about one tenth the mass of the
sun and it becomes internally unstable and breaks up into smaller
concentrations.
Within each Proto-planet, the heavier elements tend to settle towards
the centre and the lighter particles and gases remain in outer shells.
It visualises a slightly flattened and slowly rotating disc-shaped solar
nebula bulging out from the equator of the sun.
In composition, this cloud is similar to the sun and contains mostly
hydrogen and helium with small amounts of heavier elements, but the
disc and the sun itself are thought of as being cool.

2. Bi-parental origin of the earth
• It is was proposed by Chamberlin and Moulton, "as another star
approached the sun, tremendous tides were set up on the surface of the
sun and these tides or filaments of hot gases were pulled out from the
sun.
• As the star passed, these arms of gas were given a rotational motion.
• After the star was gone, the gaseous matter in these arms condensed
into solid material and gradually drew together to form planets,

3. Big Bang Theory
• The Big Bang theory provides the explanation about at the very
beginning of our universe.
• According to the theory, our universe jumped into existence as
“Singularity" around 13.7 billion years ago.
• They are thought to exist at the core of "black holes“. Where Black
holes are areas of intense gravitational pressure.
• The pressure is thought to be so intense that finite matter is actually
squished into infinite density.
• These zones of infinite density are called “Singularities“. Our universe
is thought to have begun as an infinitesimally small, infinitely hot,
infinitely dense, something - a singularity.
• After its initial appearance, it apparently inflated, expanded and cooled,
going from very-very small and very-very hot to the size and
temperature of our current universe. It continues to expand and cool to
this day and we are inside of it.

4. Big Bang Theory - Evidence for the Theory
• First of all, we are reasonably certain that the universe had a beginning.
• Second, galaxies appear to be moving away from us at speeds proportional
to their distance. This is called "Hubble's Law," named after Edwin Hubble
(1889-1953) who discovered this phenomenon in 1929. This observation
supports the expansion of the universe and suggests that the universe was
once compacted.
• Third, if the universe was initially very, very hot as the Big Bang suggests,
we should be able to find some remnant of this heat. In 1965, Radio
astronomers Arno Penzias and Robert Wilson discovered a 2.725 degree
Kelvin (-454.765 degree Fahrenheit, -270.425 degree Celsius) Cosmic
Microwave Background radiation (CMB) which spread through the
observable universe.
• Sufficiently distant light sources (generally more than a few million light
years away) show redshift corresponding to the rate of increase of their
distance from Earth.
• Finally, the abundance of the "light elements" Hydrogen and Helium found
in the observable universe are thought to support the Big Bang model of
origins.

5. Cosmic microwave background radiation
• In cosmology, cosmic microwave background (CMB)
radiation (also CMBR, CBR,MBR, and relic radiation) is thermal
radiation filling the observable universe almost uniformly.
• With a traditional optical telescope, the space between stars and
galaxies (the background) is completely dark.
• However, a sufficiently sensitive radio telescope shows a faint
background glow, almost exactly the same in all directions, that is not
associated with any star, galaxy, or other object.
• This glow is strongest in the microwave region of the radio spectrum.
• Cosmic background radiation is well explained as radiation left over
from an early stage in the development of the universe, and its
discovery is considered a landmark test of the Big Bang model of the
universe.

6. • When the universe was young, before the formation of stars and
planets, it was smaller, much hotter, and filled with a uniform glow
from its white-hot fog of hydrogen plasma.
• As the universe expanded, both the plasma and the radiation filling it
grew cooler.
• When the universe cooled enough, protons and electrons could form
neutral atoms.
• These atoms could no longer absorb the thermal radiation, and the
universe became transparent. Cosmologists refer to the time period
when neutral atoms first formed as the recombination epoch.
• The event shortly after of photons starting to travel freely through
space rather than constantly scattering with electrons and protons in
plasma is referred to as photon decoupling.
• The photons that existed at the time of photon decoupling have been
propagating ever since, though growing fainter and less energetic, since
the expansion of space causes their wavelength to increase over time
(and wavelength is inversely proportional to energy according to
Planck's relation).

7. Redshift
• In physics (especially astrophysics), redshift happens when light seen
coming from an object that is moving away,
is proportionally increased in wavelength, or shifted to
the redden/flush of the spectrum.
• Redshifts are attributable to the Doppler effect, familiar in the changes
in the apparent pitches of sirens and frequency of the sound
waves emitted by speeding vehicles and occurs due to the Doppler
effect whenever a light source moves away from an observer.
• Cosmological redshift is seen due to the expansion of the universe,
and sufficiently distant light sources (generally more than a few
million light years away) show redshift corresponding to the rate of
increase of their distance from Earth.

8. • Finally, gravitational redshifts are a relativistic effect
observed in electromagnetic radiation moving out
of gravitational fields.
• Conversely, a decrease in wavelength is
called Blueshift and is generally seen when a light-emitting
object moves toward an observer or when electromagnetic
radiation moves into a gravitational field.
• Although observing redshifts and blueshifts have several
terrestrial applications (e.g.,Doppler radar and radar
guns), redshifts are most famously seen in
the spectroscopic observations of astronomical objects.

9. Black Hole
• A black hole is a region of space-time where gravity prevents anything,
including light, from escaping.
• The theory of general relativity predicts that a sufficiently
compact mass will deform space-time to form a black hole.
• Around a black hole there is a mathematically defined surface called
an event-horizon that marks the point of no return.

10. • It is called "black" because it absorbs all the light that hits
the horizon, reflecting nothing, just like a perfect black
body in thermodynamics.
• Black holes of stellar mass are expected to form when very
massive stars collapse at the end of their life cycle.
• After a black hole has formed it can continue to grow by
absorbing mass from its surroundings.
• By absorbing other stars and merging with other black
holes, supermassive black holes of millions of solar masses
may form. There is general consensus that supermassive
black holes exist in the centers of most galaxies.

11. Kepler’s laws of planetary motion
The first and second laws (Fig.) were published in 1609 and the
third law appeared in 1619. The laws may be formulated as
follows:
• The orbit of each planet is an ellipse with the Sun at one focus;
• The orbital radius of a planet sweeps out equal areas in equal
intervals of time;
• The ratio of the square of a planet’s period (T2) to the cube of
the semi-major axis of its orbit (a3) is a constant for all the
planets, including the Earth.

12. Significance Kepler’s
• Kepler’s three laws are purely empirical, derived from
accurate observations. In fact they are expressions of more
fundamental physical laws.
• The elliptical shapes of planetary orbits described by the
first law are a consequence of the conservation of energy of
a planet orbiting the Sun under the effect of a central
attraction that varies as the inverse square of distance.
• The second law describing the rate of motion of the planet
around its orbit follows directly from the conservation of
angular momentum of the planet.
• The third law results from the balance between the force of
gravitation attracting the planet towards the Sun and the
centrifugal force away from the Sun due to its orbital
speed.

13. Bode’s law
• In 1772 the German astronomer Johann Bode devised an empirical formula to
express the approximate distances of the planets from the Sun.
• A series of numbers is created in the following way: the first number is zero, the
second is 0.3, and the rest are obtained by doubling the previous number. This
gives the sequence 0, 0.3, 0.6, 1.2, 2.4, 4.8, 9.6, 19.2, 38.4, 76.8, etc. Each
number is then augmented by 0.4 to give the sequence: 0.4, 0.7, 1.0, 1.6, 2.8,
5.2, 10.0, 19.6, 38.8, 77.2, etc. This series can be expressed mathematically as
follows:
dn=0.4, for n=1 and dn=0.4+0.3 x2n-2 for n>2

14. • This expression gives the distance dn in astronomical units
(AU) of the nth planet from the Sun. It is usually known as
Bode’s law but, as the same relationship had been suggested
earlier by J. D. Titius of Wittenberg, it is sometimes called
Titius–Bode’s law.

15. Formation of Moon
• For a long period of time, the fundamental question
regarding the history of the Moon was of its origin.
• Early hypotheses included
i) fission from the Earth,
ii) capture
iii) co-accretion.
iv) Today, the giant impact hypothesis is widely accepted by
the scientific community

16. Fission hypothesis
• The idea that the ancient Earth, with an accelerated
rotation, expelled (split up) a part of its mass, was
proposed by George Darwin (son of the famous
biologist Charles Darwin).
• It was commonly assumed that the Pacific
Ocean represented the scar of this event.
• However, today it is known that the oceanic crust that
makes up this ocean basin is relatively young, about 200
million years old or less, whereas the Moon is much older.
• However, the fact that the Pacific is not the result of lunar
creation does not disprove fission theory.
• This hypothesis also cannot account for the angular
momentum of the Earth-Moon system.

17. Lunar capture
• This hypothesis states that the Moon was captured,
completely formed, by the gravitational field of the Earth.
• This is doubtful, since a close encounter with the Earth
would have produced either a collision or an alteration of
the trajectory of the body in question, so if it had indeed
happened, the Moon probably would never return to meet
again with the Earth.
• For this hypothesis to function, there would have to be a
large atmosphere extended around the primitive Earth,
which would be able to slow the movement of the Moon
before it could escape.
• This hypothesis has difficulty in explaining the essentially
identical oxygen isotope ratios of the two worlds.

18. Co-accretion hypothesis
• This hypothesis states that the Earth and the Moon formed
together as a double system from the ancient accretion
disk of the Solar System.
• The problem with this hypothesis is that it does not explain
the angular momentum of the Earth-Moon system or why
the Moon has a relatively small iron core compared to the
Earth (25% of its radius compared to 50% for the Earth)

19. Giant impact theory
• At present the most widely accepted explanation for the
origin of the Moon involves a collision of two proto-
planetary bodies during the early accretional period of Solar
System evolution.
• This "giant impact theory", satisfies the orbital conditions of
the Earth and Moon and can account for the relatively small
metallic core of the Moon.
• Collisions between planetesimals are now recognized to lead
to the growth of planetary bodies early in the evolution of
the Solar System.

20. • A widely accepted theory of planet formation, the so-called
planetesimal hypothesis of Viktor Safronov, states that
:planets form out of cosmic dust grains that collide and stick to
form larger and larger bodies. When the bodies reach sizes of
approximately one kilometer, then they can attract each other
directly through their mutual gravity, enormously aiding further
growth into moon-sized protoplanets.
• It is generally believed that about 3.8 billion years ago, after a
period known as the Late Heavy Bombardment, most of the
planetesimals within the Solar System had either been ejected
from the Solar System entirely, into distant eccentric orbits, or
had collided with larger objects due to the regular gravitational
bump from the Jovian planets (particularly Jupiter and Neptune)

21. LUNAR Landscape
• The lunar landscape is characterized by impact craters, their
ejecta, a few volcanoes, hills, lava flows and depressions filled
by magma.

22. Lunar topography
• The moon contains a ~70-km thick basaltic crust that
differentiated from a denser, underlying mantle at least 4.4
billion years ago.
• The crustal rocks returned by the Apollo Mission range in age
from 4.3 to 3.1 billion years old. In contrast, the oldest rocks on
earth are rarely more than 3 billion years old.
• The lunar crust is easily discernible into two primary types of
terrains: the older highlands, which comprise about 83% of the
lunar surface (light regions in image), and the younger
lunar maria, which comprise the remaining 17% (dark regions).
• The heavily cratered highlands are covered with a layer
of regolith, a mixture of fine dust and fragmented debris
generated by meteorite impacts. Beneath the regolith, two
crustal rocks types dominate the highlands.

23. The highlands
• The most distinctive aspect of the Moon is the contrast between
its bright and dark zones.
• Lighter surfaces are the lunar highlands and the darker plains
are called maria (singular mare, from the Latin for sea).
• The highlands are anorthositic in composition, whereas the
maria are basaltic.
• The maria often coincide with the "lowlands," but it is important
to note that the lowlands (such as within the South Pole-Aitken
basin) are not always covered by maria.
• The highlands are older than the visible maria.

24. The lunar maria
• The lunar maria (singular: mare) are large, dark, basaltic plains on
Earth's Moon, formed by ancient volcanic eruptions.
• They were dubbed maria, Latin for "seas", by early astronomers who
mistook them for actual seas.
• The lunar maria are large flows of basaltic lava, that correspond to low-
albedo surfaces, covering nearly one third of the near-side. Only a few
percent of the far-side has been affected by mare volcanism.
• They are less reflective than the "highlands" as a result of their iron-rich
compositions, and hence appear dark to the naked eye.
• The ages of the mare basalts have been determined both by
direct radiometric dating and by the technique of crater counting.
• The oldest radiometric ages are about 4.2 Ga, whereas the youngest ages
determined from crater counting are about 1 Ga (1 Ga = 1 billion years).
• Most of the mare formed between about 3 and 3.5 Ga. The maria are
clearly younger than the surrounding highlands given their lower density
of impact craters.

25.  Rille
• Rille (German for 'groove/ channel') is typically used to describe any of the
long, narrow depressions in the lunar surface that resemble channels.
Typically a rille can be up to several kilometers wide and hundreds of
kilometers in length. Based on observations from the Apollo mission, it is
generally believed that this rille was formed by volcanic processes.
 lunar dome
• A lunar dome is a type of shield volcano that is found on the
surface of the Earth's Moon. They are typically formed by highly
viscous, possibly silica-rich lava, erupting from localized vents
followed by relatively slow cooling. Lunar domes are wide,
rounded, circular features with a gentle slope rising in elevation
a few hundred meters to the mid-point. They are typically 8-12
km in diameter, but can be up to 20 km across.

26.  Wrinkle ridges
• Wrinkle ridges are features created by compressive tectonic forces within
the maria, when the basaltic lava first cooled and contracted. These
features represent buckling of the surface and form long ridges across parts
of the maria. Some of these ridges may outline buried craters or other
features beneath the maria. They frequently outline ring structures buried
within the mare, follow circular patterns outlining the mare, or intersect
protruding peaks. A prime example of such an outlined feature is the
crater Letronne.
 Graben
• Grabens are tectonic features that form under extension
stresses. Structurally, they are composed of two normal faults,
with a down-dropped block between them. Most grabens are
found within the lunar maria near the edges of large impact
basins.
•

27. Impact craters
• Impact crater is the most notable geological process on the Moon. The
craters are formed when a solid body, such as an asteroid or comet, collides
with the surface at a high velocity (mean impact velocities for the Moon are
about 17 km per second). The kinetic energy of the impact creates a
compression shock wave that radiates away from the point of entry. This is
succeeded by a rarefaction wave, which is responsible for propelling most of
the ejecta out of the crater. Finally there is a hydrodynamic rebound of the
floor that can create a central peak.
•
• The most recent impacts are distinguished by well-defined features, including
a sharp-edged rim. Small craters tend to form a bowl shape, while larger
impacts can have a central peak with flat floors. Larger craters generally
display slumping features along the inner walls that can form terraces and
ledges.
•

28. Regolith or Lunar Soil
• The surface of the Moon has been subject to billions of years of collisions
with both small and large asteroid and comet
• Over time, these impact processes have broken up and crushed the surface
materials, forming a fine grained layer termed "regolith".
• The thickness of the regolith varies between 2 meters beneath the younger
maria, to up to 20 meters beneath the oldest surfaces of the lunar highlands.
• The regolith is predominantly composed of materials found in the region,
but also contains traces of materials ejected by distant impact craters.
• The term "mega-regolith" is often used to describe the heavily fractured
bedrock directly beneath the near-surface regolith layer.

29. Regolith or Lunar Soil
• The regolith contains rocks, fragments of minerals from the original
bedrock, and glassy particles formed during the impacts.
• In most of the lunar regolith, half of the particles are made of mineral
fragments fused by the glassy particles.
• The chemical composition of the regolith varies according to its location; the
regolith in the highlands is rich in aluminum and silica, just as the rocks in
those regions.
• The regolith in the maria is rich in iron and magnesium and is silica-poor, as
the basaltic rocks from which it is formed.
• The lunar regolith is very important because it also stores information about
the history of the Sun.
• The atoms that compose the solar wind –
mostly helium, neon, carbon and nitrogen – hit the lunar surface and insert
themselves into the mineral grains.
• Upon analyzing the composition of the regolith, particularly
its isotopic composition, it is possible to determine if the activity of the Sun
has changed with time.

30. Lunar lava tubes
• Lunar lava tubes form a potentially important location for constructing a
future lunar base,
• Which may be used for local exploration and development, or as a human
outpost to serve exploration beyond the Moon.
• A lunar lava cave potential has long been suggested and discussed in
literature and thesis.
• Any undamaged lava tube on the moon could serve as a shelter from the
severe environment of the lunar surface, with its frequent meteorite
impacts, high-energy ultraviolet radiation and energetic particles, and
extreme diurnal temperature variations.

32. Internal structure of Moon
• The current model of the interior of the Moon was derived
using seismometers left behind during the manned Apollo
program missions, as well as investigations of the Moon's gravity field and
rotation.
• The crust of the Moon is on average about 50 km thick (though this is
uncertain by about ±15 km, ).
• It is widely believed that the far-side crust is on average thicker than the
near side by about 15 km.
• Seismology has constrained the thickness of the crust only near the Apollo
12 and 14 landing sites.
• While the initial Apollo-era analyses suggested a crustal thickness of about
60 km at this site,
• Recent re-analyses of this data set suggest a thinner value, somewhere
between about 30 and 45 km.

34. Core
• In 2010 reanalysis of the old Apollo seismic data on the deep moonquakes
using modern processing methods confirmed that the Moon has an iron
rich core with the radius of 330 ± 20 km.
• The same reanalysis established that the solid inner core made of pure iron
has the radius of 240 ± 10 km.
• The core is surrounded by the partially (10 to 30%) melted layer of the
lower mantle with the radius of 480 ± 20 km (thickness ~150 km).
• These results imply that 40% of the core by volume has solidified. The
density of the liquid outer core is about 5 g/cm3 and it can contain as much
6% sulfur by weight. The temperature in the core is probably about 1600–
1700 C.

35. Lunar Magnetic field
• Compared to that of Earth, the Moon has only a very weak external
magnetic field.
• Other major differences are that the Moon does not possess a
dipolar magnetic field like the Earth does (as would be generated by
a geodynamo in its core),
• the magnetizations that are present are almost entirely crustal in origin.
• One hypothesis holds that the crustal magnetizations were acquired early in
lunar history when a geodynamo was still operating. The small size of the
lunar core, however, is a potential obstacle to this theory.
• Alternatively, it is possible that on airless bodies such as the Moon,
transient magnetic fields could be generated during impact processes. In
support of this, it has been noted that the largest crustal magnetizations
appear to be located near the antipodes of the largest impact basins.