4.2
1.For every type of matter particle we've found, there also exists a corresponding antimatter particle, or antiparticle.
Antiparticles look and behave just like their corresponding matter particles, except they have opposite charges. For instance, a proton is electrically positive whereas an antiproton is electrically negative. Gravity affects matter and antimatter the same way because gravity is not a charged property and a matter particle has the same mass as its antiparticle.
When a matter particle and antimatter particle meet, they annihilate into pure energy! 
When a particle and its antiparticle collide, both can be annihilated and other particles such as photons or pions produced. In some cases this represents the total conversion of mass into energy.
2. There are two forces in GTU era namely gravity and GUT force.
3. The universe in particle era reached an age of 1 millisecond, the quarks in the particle era combine in groups of three to form protons and neutrons because of the low temperature of the universe in this era.
4. 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 Bangplasma. As the universe expanded, both the plasma and the radiation filling it grew cooler. When the universe cooled enough, stable atoms could form. These atoms could no longer absorb the thermal radiation, and the universe became transparent instead of being an opaque fog. The photons that existed at that time have been propagating ever since, though growing fainter and less energetic, since exactly the same photons fill a larger and larger universe. This is the source for the alternate term relic radiation. model of the universe. 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
4.3
1. 
2. Nuclear fusion is when two small atoms collide to produce a larger atom. Since nuclei have a positive charge, they will repel each other. However, if they get close enough, the will "stick" together. It takes a lot of energy to get the nuclei close enough to stick together. Temperature is really just a measure of how fast atoms are bouncing around off each other. The higher the temperature, the faster atoms are moving around, and the more likely they will be to collide and stick, or fuse, to each other. The same goes with pressure. The higher the pressure, the more atoms you have in a smaller space, the more likely they are to fuse with each other.
3. Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature. Sunspots are regions on the solar surface that appear dark because they are cooler than the surrounding photosphere, typically by about 1500 K (thus, they are still at a temperature of about 4500 K, but this is cool compared to the rest of the photosphere). They are only dark in a relative sense; a sunspot removed from the bright background of the Sun would glow quite brightly.
4. Stars that begin with more than 50 solar masses can lose over half their total mass while they remain on the main sequence. The duration that a star spends on the main sequence depends primarily on the amount of fuel it has to fuse and the rate at which it fuses that fuel, i.e. its initial mass and its luminosity. For the Sun, this is estimated to be about 1010 years. Large stars consume their fuel very rapidly and are short-lived. Small stars (called red dwarfs) consume their fuel very slowly and last tens to hundreds of billions of years. At the end of their lives, they simply become dimmer and dimmer.[2] However, since the lifespan of such stars is greater than the current age of the universe (13.7 billion years), no red dwarfs are expected to have yet reached this state.
4.4
1. The elliptical galaxy has a round or oval shape the spiral galaxy has a hurricane shape. The origin of these different shapes would lie in the particular momentum of the constituent stars at the time they first coalesced into a galaxy under their mutual gravitational attraction. Spiral galaxies usually consist of two major components: A flat, large disk which often contains a lot of interstellar matter (visible sometimes as reddish diffuse emission nebulae, or as dark dust clouds) and young (open) star clusters and associations, which have emerged from them (recognizable from the blueish light of their hottest, short-living, most massive stars), often arranged in conspicuous and striking spiral patterns and/or bar structures, and an ellipsoidally formed bulge component, consisting of an old stellar population without interstellar matter, and often associated with globular clusters. Elliptical galaxies are actually of ellipsoidal shape.Normally, elliptical galaxies contain very little or no interstellar matter, and consist of old population II stars only: They appear like luminous bulges of spirals, without a disk component.
2. A spiral galaxy CAN be called a spiral barred galaxy if it has a central bar. About 50% of all spiral galaxies have a central bar. It's nothing more than a central core than resembles a bar - or peanut in earlier texts that differentiate it from "normal" spiral galaxies that have a circular or oval centre.
3. In 1929, Edwin Hubble announced that almost all galaxies appeared to be moving away from us. This phenomenon was observed as a redshift of a galaxy's spectrum. This redshift appeared to have a larger displacement for faint, presumably further, galaxies. Hence, the farther a galaxy, the faster it is receding from Earth. The Hubble constant is given by H = v/d , where v is the galaxy's radial outward velocity, d is the galaxy's distance from earth, and H is the current value of the Hubble constant.
4.5
1. Scientists believe that the solar system was formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star (called a supernova). This explosion made waves in space which squeezed the cloud of gas and dust. Squeezing made the cloud start to collapse, as gravity pulled the gas and dust together, forming a solar nebula. Just like a dancer that spins faster as she pulls in her arms, the cloud began to spin as it collapsed. Eventually, the cloud grew hotter and denser in the center, with a disk of gas and dust surrounding it that was hot in the center but cool at the edges. As the disk got thinner and thinner, particles began to stick together and form clumps. Some clumps got bigger, as particles and small clumps stuck to them, eventually forming planets or moons . Near the center of the cloud, where planets like Earth formed, only rocky material could stand the great heat. Icy matter settled in the outer regions of the disk along with rocky material, where the giant planets like Jupiter formed. As the cloud continued to fall in, the center eventually got so hot that it became a star, the Sun, and blew most of the gas and dust of the new solar system with a strong stellar wind. By studying meteorites, which are thought to be left over from this early phase of the solar system, scientists have found that the solar system is about 4,600 million years old!
- The jovian planetesimals soon became the icy, dense cores we see today surrounded by huge clouds of accreted gas. Much like the collapse of the solar nebula, these balls of gas can grow large enough to induce gravitational collapse. Remember from the star formation section that gravitational collapse involves heating up, flattening out and rotating faster. It is possible that as the jovian protoplanets collapsed, smaller particles in the surrounding disk formed into some of the moons that now orbit the individual outer planets. This makes sense, since the outer planets all have many moons and rings that orbit in the same plane, just like the planets in our solar system orbit the Sun in the same plane. These pieces gradually grow larger in a process called accretion.
3. The four Jovian planets in our solar system are Jupiter, Saturn, Uranus and Neptune. The four terrestrial planets are Earth, Venus, Mars and Mercury. The difference between the Jovian planets and the terrestrial planets is that Jovian planets are enormous and made of gasses and ices while terrestrial planets are relatively small and made of rocks and metals. Other differences are that terrestrial planets have high densities, rotate slowly, have no moons or magnetic fields and have thin atmospheres (Earth is an exception because it has a moon and a magnetic field), while Jovian planets have low densities, rotate rapidly, have many moons and a magnetic field and have thick atmospheres.
4. The Kuiper belt was initially believed to be the main repository for periodic comets, those with orbits lasting less than 200 years. However, studies since the mid-1990s have shown that the Kuiper belt is dynamically stable, and that their true place of origin is the farther scattered disc, a dynamically active region created by the outward motion of Neptune 4.5 billion years ago;[9]Eris are KBO-like bodies with extremely large orbits that take them as far as 100 AU from the Sun. scattered disc objects such as
Pluto is the largest known member of the Kuiper belt. Originally considered a planet, Pluto's position as part of the Kuiper belt has caused it to be reclassified as a "dwarf planet". It is compositionally similar to many other objects of the Kuiper belt, and its orbital period is identical to that of the KBOs known as "plutinos". In Pluto's honour, the four currently accepted dwarf planets beyond Neptune's orbit are called "plutoids".
5. The Oort cloud is an immense spherical cloud surrounding the planetary system and extending approximately 3 light years, about 30 trillion kilometers from the Sun. This vast distance is considered the edge of the Sun's orb of physical, gravitational, or dynamical influence.
Within the cloud, comets are typically tens of millions of kilometers apart. They are weakly bound to the sun, and passing stars and other forces can readily change their orbits, sending them into the inner solar system or out to interstellar space. This is especially true of comets on the outer edges of the Oort cloud. The structure of the cloud is believed to consist of a relatively dense core that lies near the ecliptic plane and gradually replenishes the outer boundaries, creating a steady state. One sixth of an estimated six trillion icy objects or comets are in the outer region with the remainder in the relatively dense core.
5. The IAU currently recognizes five dwarf planets—Ceres, Pluto, Haumea, Makemake, and Eris.[7]absolute magnitude brighter than +1 (and hence a mathematically delimited minimum diameter of 838 km[8]) are to be named under the assumption that they are dwarf planets. The only two such objects known at the time, Makemake and Haumea, went through this naming procedure and were declared to be dwarf planets. However, only two of these bodies, Ceres and Pluto, have been observed in enough detail to demonstrate that they fit the definition. Eris has been accepted as a dwarf planet because it is more massive than Pluto. The IAU subsequently decided that unnamed trans-Neptunian objects with an
