Astronomy Test 2

How do crater counts tell us the age of a surface? Explain why the moon has so many more craters than earth.

- Because most of the Earth's impact craters have been covered overtime by geological processes such as volcanic eruptions and erosion. - More craters indicate older surface. A geological surface looks about the same as it did billions of years ago.

Outline the general origin and evolution of the Earth's atmosphere, oceans, and land masses.

-4.6 BYA: Earth formed by meteor impacts and surface was molten (differentiation: dense material sinks to the middle, light material stays at the top and freezes into rock crust) -4.0 BYA: water condensed, rained for millions of years -3.5 BYA: evidence of life (stromatolites), land forming from granite -2.5 BYA: oxygen atmosphere from photosynthesis -1.5 BYA: blue oceans and sky, plate tectonics -700 MYA: "snowball" Earth -600 MYA: multicellular life -542 MYA: Cambrian Explosion -400 MYA: land animals, complex plants, forests -250 MYA: Permian extinction (Siberian lava plume) -240 MYA: Pangea -220 MYA: dinosaurs -180 MYA: Pangea broke up -65 MYA: dinosaurs done-zo -2.3-5.3 MYA: today's continents -2-3 MYA: first humans walking

Describe the modern scenario for the formation of the Solar System.

-A floating cloud collapsed and flattened into a disk -Dense, hot material sunk to the center -Light, cold material clumped into dust and the clumps grew into planets -middle of the disk got so hot that hydrogen and helium fused into the Sun -Terrestrial planets were too hot for hydrogen and helium to stay, so they formed the atmospheres of the colder Jovian planets -Ice and other leftover objects made asteroids

Briefly summarize the evidence linking human activity to global warming. What are its potential consequences?

-Burning of fossil fuels- increasing the atmospheric concentration of carbon dioxide and other greenhouse gases which leafs to global warming. -Polar regions melting- species suffer as more salt water mixes with fresh water -gulf is warmer- more hurricanes more severe blizzards -fresh water ay alter ocean currents- gulf stream -sea level rising- water expands when it is warmer, floods in low lands

Compare and contrast the Jovian planets as a group to the terrestrial planets, emphasizing the 3 biggest differences.

-Jovian planets are gas giants with small cores or possibly no cores -terrestrial planets are made of rock and iron -Jovian planets significantly larger -Colder than terrestrial planets, because they are farther away from the Sun (cold enough for gas to condense) -Jovian atmospheres mostly consist of hydrogen and helium, with other amounts of methane, ammonia, and water -Terrestrial planets are mostly nitrogen, carbon dioxide, oxygen, argon, and water vapor -Outer planets rotate faster than inner planets -Outer planets have more natural satellites -Inner planets have larger densities

Identify at least three dynamic and/or physical properties of the solar system as a whole that any model of the origin of the system must explain.

-Must explain why planets fall into two major categories: terrestrial and jovian planets -Must explain existence of huge numbers of asteroids and comets, and why they are located in the asteroid belt, Kuiper Belt, and Oort Cloud -Must explain general patterns while at the same time making allowances for exceptions to general rules, such as the odd axis tilt of Uranus and existence of Earth's moon

Discuss the composition, structure, and stability of Saturn's rings.

-Made up of trillions of boulders, ice -Less than one km thick, hundreds of km wide -Shepherd moons organize the rings through gravity, creates gaps in rings

Identify the unique property of Titan.

-Only moon with atmosphere (thicker than Earth's) -Has weather, rivers, lakes -Except they're liquid methane and ammonia -Life? (because of sunlight and methane is a hydrocarbon)

Identify the unique circumstances of Neptune's discovery.

-Only planet discovered by mathematical calculations -Can only be seen telescopically

Describe the conditions that would cause us to see each of the three basic types of spectra. What do we see in the Sun's spectrum shown on the opening page of this chapter?

1. Continuous Spectrum - light like the rainbow 2. Absorption Line Spectrum - dark lines on a continuous spectrum (used for astronomy and remote sensing) 3. Emission Line Spectrum - mostly dark, no continuity (electromagnetic radiation) radio waves, gamma waves

Describe four ways in which earth is unique among the terrestrial worlds, and how each is important to life.

1. Earth retains most of its outgassed water- temps were low enough for water vapor to condense into rain and form oceans 2. Earth has very little carbon dioxide- oceans explain why there is little CO2 because most CO2 outgassed by volcanism on earth dissolved into the oceans 3. Composed primarily of nitrogen and oxygen- nitrogen is the 3rd most common gas released by outgassing; oxygen would disappear from our atmosphere if not continuously resupplied/ LIFE, plants, photosynthesis 4. Has an ultra violet absorbing stratosphere- life and oxygen, chemical reactions form some of the O2 molecules into O3(ozone), absorbs solar ultraviolet energy because it is more weakly bound surface liquid water more simply surface liquid water atmospheric oxygen plate tectonics climate stability

List the 4 largest moons of Jupiter (in order of increasing distance) as well as basic features of each.

1. Io (closest, roughly same size of Earth's moon) -Most volcanically active body in the solar system -Has elliptical orbit around Jupiter 1 1/2 days -Gravitational tides heat the interior--volcanism 2. Europa (second closest) -No craters -Surface is frozen -Experiences smaller gravitational tides that crack the surface and hot liquid water resurfaces planet and it freezes again -Life? 3. Ganymede (third closest, largest moon in SS) -Craters -magnetic field -Little geological activity -Possible liquid water ocean under crust 4. Callisto (fourth closest) -Craters All are tidally locked with Jupiter

What are the two major approaches to detecting extrasolar planets indirectly?

1. Observing the motion of a star to detect the subtle gravitational effects of orbiting planets. 2.Observing changes to a star's brightness that occur when one of its planets passes in front of the star as viewed from Earth.

Why are extrasolar planets hard to detect directly?

A Sun-like star is about a billion times brighter than the sunlight reflected from its planets, and trying to see it at that distance is like being in San Francisco and trying to see a pinhead 15 meters from a grapefruit in Washington, D. C.

What produces the coma and tails of a comet? What is the nucleus? Why do tails point away from the Sun?

A comet approaching the Sun causes the temperature to increase and ices begin to sublimate into gas. Gas drags away dust particles. Gas and dust create the coma, the atmospheric halo around the nucleus, Jets and gas shooting out at great speeds creating tails. UV light from the Sun ionizes the gas and the solar wind carries the gas outward away from the Sun

Viewed through a telescope, much of Orion Nebula looks like a glowing cloud of gas. What type of spectrum would you expect to see from the glowing parts of the nebula? why?

A glowing cloud of gas will produce an emission line spectrum, because the hot gas will emit light as electrons fall from higher energy levels to lower ones.

Isotope

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

What is now thought to cause Earth's recent global warming?

Burning coal and other fossil fuels has released CO2 into the atmosphere which in turn traps heat and warms the Earth.

Describe the greenhouse effect.

Carbon dioxide in the atmosphere traps the sun's heat but does not release it.

Describe the process of cratering and tell how craters can be used to infer the relative ages of surfaces.

Craters are made by meteor impacts, and planets that are geologically active will essentially repave their surface and cover the craters. Planets or moons with lots of craters can be inferred to be geologically inactive.

What are the strengths and limitations of the Doppler and transit techniques? What kinds of planets are easiest to detect with each method? Are there certain planets that each method connote detect, even if the planets are very large? Explain. What are the advantages if a plant can be detected by both methods?

Doppler: provide minimum masses; easier to detect large planets Transit: provide sizes, and sometimes atmospheric composition and temperature; easier to detect large planets Both: average density

What is electrical charge? Will an electron and a proton attract or repel one another? How about two electrons?

Electrical charge is a measure of how strongly something will interact with electromagnetic fields. We define a proton as having +1 unit of charge and an electron as having -1 unit when talking about atoms and particles. Two particles with charges of different sign will attract each other, so protons and electrons will attract. Particles with charges of the same sign will repel each other, so two electrons will repel each other.

Archaeologists learn that the fall of ancient Rome was caused in large part by an asteroid impact in Asia.

Extremely unlikely

New photographs reveal sand dunes on Mercury.

False, Our current observations of Mercury show it covered by craters, and absolutely barren of water or an atmosphere. Since sand dunes are built up by erosion cause either by winds of an atmosphere or of currents in water, we therefore wouldn't expect to see sand dunes since we see neither water nor air on Mercury.

Seismic studies on Earth reveal a "lost continent" that held great human cities just a few thousand years ago but that is now buried deep underground off the western coast of Europe.

False, This is not plausible. Plates move only a few centimeters per year, so a continent could not be sub-ducted in a few thousand years. Neither could erosional processes bury a continent on the time scale of human civilization.

We find a planet in another solar system that has Earth-like plate tectonics; the planet is the size of the Moon and orbits 1 AU from its star

False, This would be incredibly unlikely because we expect only a larger world to have plate tectonics. However, it might be possible if the planet is young and still hot inside.

Clear cutting in the Amazon rain forest on earth exposes terrain that is as heavily cratered as the lunar highlands.

False, This would be surprising. Erosion has been so strong in that region that no ancient terrain would be recognizable. Furthermore, Earth had little continental crust so long ago that South America wouldn't even have existed as a large land mass at that time.

We find a planet in another solar system that is as large as Earth but as heavily cratered as the Moon.

False, This would be surprising. Such a large planet would be expected to have extensive geological activity from volcanism, tectonics, and probably erosion.

In another solar system, astronomers discover an object the size of Earth orbiting its star at the distance of the kupier belt.

False, this is most likely false because, Terrestrial planets are not expected to form in regions where ice is common.

If fusion in the solar core suddenly ceased today, worldwide panic would break out tomorrow as the Sun began to grow dimmer

False. It takes about a million years for light to get from the core to the surface, so we wouldn't notice anything for a while

The fact that we have not yet discovered an Earth-size extrasolar planet tells us that such planets must be very rare

False; That or the technology we have isn't that advanced just yet to be able to find more like Earth

How do we think hot Jupiters formed? Why didn't a hot Jupiter form in our solar system?

Hot Jupiters formed beyond the frost line, as in our solar system, and migrated inward due to interaction with the solar nebula. Because the nebula must have dispersed shortly after the formation of our jovian planets.

Which describes our understanding of flowing water on Mars?

It was important once, but no longer

What would happen if a 1-kilometer object struck Earth?

It would cause widespread devastation and climate change

Based on current evidence, how common are planetary systems?

Kepler spacecraft had discovered in total several thousand planet candidates during all the time of its operation, most of them are thought to be real planets.

The asteroid belt lies between the orbits of...

Mars and Jupiter

How do mathematical models help us learn about conditions inside the Sun?

Mathematical models use the observed composition and mass of the Sun along with the laws of physics to derive equations that describe the gravitational equilibrium, solar thermostat, and rate at which energy moves from the core to the photosphere.

Compare the sizes, masses, and densities of the planets and major moons to each other. For smaller planets, compare surface temperatures and atmospheres.

Mercury -Density of 5400, .0553 solar mass -Surface temp 700 (daytime) and -200 (nighttime) -No atmosphere, no moons, geologically dead Venus -Density of 5200, 0815 solar mass -surface temp 900 -CO2 atmosphere, no moons, geologically active Earth -Density of 5500, 1 solar mass -Surface temp 61 -Nitrogen, O2 atmosphere, 1 moon, geologically active Mars -Density of 3900, .107 solar mass -Surface temp -67 -Mostly CO2 atmosphere, hardly an atmosphere, geologically inactive Jupiter -Density of 1330, 317 solar mass -Average temp -234 -Hydrogen, helium atmosphere (with methane, ammonia) Saturn -Density of 687, 95 solar mass -Average temp -288 -Hydrogen, helium atmosphere (with methane, water ice) Uranus -Density of 1270, 14.5 solar mass -average temp -357 -hydrogen, helium atmosphere (methane makes it blue, ammonia, ice) -Neptune -Density of 1640, 17 solar mass -average temp -353 -hydrogen, helium atmosphere (methane, ammonia, ice)

List the planets ordered by their distance from the Sun.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

Describe how scientists determine what the interior of the Sun is like. Why have we not yet sent a probe into the Sun to obtain direct information about the interior?

Mostly it's inference. We know about the surface from looking at it (spectral lines, total radiation, size, power spectrum etc.) so we can model the processes inside and see if our models fit reality. We also get neutrinos directly from the interior, which (eventually) fit with our understanding of the nuclear reactions inside. a) it's hugely expensive to get there b) it would melt at the surface, and we can see the surface anyway.

What is the overall nuclear fusion reaction in the sun?

Nuclear fusion is the source of all energy the Sun releases into space. If the fusion rate is varied, so would the Sun's energy output, and large variations in the Sun's luminosity would almost surely be lethal to life on Earth. Fortunately, the Sun fuses hydrogen at a steady rate, thanks to a natural feedback process that acts as a thermostat for the Sun's interior. Solar energy production remains steady because the rate of nuclear fusion is very sensitive to temperature. A slight increase in the Sun's core temp. would mean a much higher fusion rate

What is outgassing, and how did it lead to the existence of Earths atmosphere and oceans?

Outgassing - the release of pressure expelling trapped gasses from molten rock. most gas is water which goes to oceans other 77 percent goes to atmosphere

Briefly describe the astrometric method and its strengths and limitations.

Precise measurements of stellar positions in the sky are used to look for the slight motion caused by orbiting planets. It works best for detecting binary star systems, but planet searches can be difficult using this method. It is also hard to use the method as the side to side wobble is very small at distance. The other issue is the time it takes to confirm the wobble as planets can take years to centuries to complete their orbits.

Distinguish between primitive meteorites and processed meteorites in terms of both composition and origin.

Primitive meteorites are made of carbon or stone, and originate in the solar nebula that formed the solar system. Processed meteorites are either metal-rich or rocky in composition, the metal-rich are composed like they originated in the planets core and the rocky are similar in composition to a planet's mantle or crust.

Geologists discover a crater from a 5-kilometer object that impacted Earth more than 100 million years ago

Reasonable, because its only 5km which would probably created tsunamis, or climate change..??

Outline the most accepted theory of the origin of the moon and the evidence supporting it.

Something Mars-sized crashed into Earth (after the iron sunk to the center) and the material that flew off made the Moon. The Moon's density is 3300 kg/m^3, which points to rock all the way through. Moon rocks are also chemically identical to Earth rocks. The Moon also is not experiencing gravitational friction (losing momentum, orbit decay); it is receding from Earth.

Describe the key ways in which the atmosphere affects Earth. What is greenhouse effect, and how does it work?

Surface protection - protects us from Sun's radiation (ionizing photons) Greenhouse effect - atmosphere traps additional heat (some light absorbed, some reflected. Reflected in form of infrared light. GE occurs when the atmosphere temporarily traps some of the infrared light that the ground emits, slowing its return to space.) Occurs only when the atmosphere contains gases that can absorb infrared light (greenhouse gases: H2O, CO2, methane (CH4).

A small asteroid that orbits within the asteroid belt has an active volcano.

Surprising, because asteroids are too small to have volcanic activity.

Argue from Earth's average density that the Earth's core has a dense metallic composition.

The average density of water is 1000 kg/m^3 and the average density of iron is 9000 kg/m^3. Earth's average density is 5500 kg/m^3. When water and rock are only 1000 and 3000, there is still missing density, which can only be explained by a dense iron core because lead and gold are too heavy, and rock is too light.

Why does earth have a global magnetic field? What is the magnetosphere?

The leading theory is that it is caused by the churning liquid of the earth's outer core. protects earth from solar wind This may explain why the earth's magnetic pole has shifted several times throughout the earth's history. - Magnetosphere - the region surrounding the earth or another astronomical body in which its magnetic field is the predominant effective magnetic field. also internal heat causes liquid metal to rise and fall while earths rotation twists and distorts the convection pattern

How can gravitational tugs from orbiting planets affect the motion of a star? Explain how alien astronomers could deduce the existence of planets in our solar system by observing the Sun's motion.

The planets cause the star to wobble around on the point of the system's center of mass. Someone observing our solar system could use this method called the astrometric method to detect Earth and the other planets.

Within the next few years, astronomers expect to confirm all the planet detections made with the astrometric and Doppler methods by observing transits of these same planets.

The statement doesn't make sense. Most planets are on orbits that don't pass between the star and Earth, meaning no transits occur.

Some extrasolar planets are likely to be made mostly of gold.

The statement doesn't make sense. We know of no process that enriches gold over other metals.

I wear a lead vest to protect myself from solar neutrinos.

The statement is false. Neutrinos have very low chance of interacting with matter. It can pass through a light year of lead, and does not interact with any of the lead atoms.

Scientists are currently building an infrared telescope designed to observe fusion reactions in the Sun's core.

The statement is false. Photons generated via nuclear fusion are generally in X-ray / Gamma-ray spectrum. Therefore, infrared telescope is probably useless if one wants to study nuclear fusion.

Astronomers have recently photographed magnetic fields churning deep beneath the solar photosphere

The statement is false. We can only measure magnetic fields by looking how they interact the matter. One cannot directly photograph magnetic fields. Also, it is not possible to photograph something beneath the photosphere.

News of a major solar flare today caused concern among professionals in the fields of communication and electrical power generation.

The statement is true. The charged particles released from solar flare can interrupt communication and electrical power generation.

If there are few sunspots this year, we should expect many more in about 5 years.

The statement is true. The sunspot cycle has an average period of 11 years or sometimes 22 years. Assuming we are at the lowest point of the cycle, the number of sunspots should increase the next 5 years.

Some extrasolar planets are likely to be made mostly of water.

The statement makes sense. Water worlds have already been discovered.

Identify the cause of geologic activity on Jupiter's inner moons.

The strong gravitational force of Jupiter combined with the tidal resonance between Io, Europa and Callisto causes geological activity. As a result the moons are alternatively stretched and squeezed

Helium (He)

two protons, two neutrons, two electrons

How do magnetic fields keep sunspots cooler than the surround- ing plasma? Explain

They separate the sunspot's gas from the rest of the Sun's surface gas. This prevents them from mixing and heating the sunspot back to the average surface temperature.

Studies of a large object in the Kuiper belt reveal that it is made almost entirely of rocky ( as opposed to icy) material.

This is borderline between surprising and expected. Most objects in the Kuiper Belt are mixtures of rock and ice, but it is possible to find an object which is mostly just rock.

Astronomers discover a previously unknown comet that will be brightly visible in out night sky about two years from now.

This is reasonable. Previously undiscovered comets can enter our orbit.

By observing solar neutrinos, we can learn about nuclear fusion deep in the Sun's core.

This statement is true. By studying solar neutrinos, we can learn about the rate of nuclear fusion inside the Sun.

If the Sun's magnetic field somehow disappeared, there would be no more sunspots on the Sun.

This statement is true. Sunspots occur because the Sun's magnetic field prevents hot gas from entering into them. If the magnetic field disappear, there can't be any more sunspots.

A mission to Eris finds that it has lakes of liquid water in its surface.

This would be surprising, because Eris is even farther than Pluto, which wouldn't be able to have water, because its too far from the Sun, it'd be to cold.

Why does nuclear fusion require high temperatures and pressures ?

To bond together, two nuclei must be thrown together with great force. This is because every nucleus has a positive charge and the nuclei repel each other when they come close. If that resistance is overcome and the nuclei actually begin to impact each other, then it is possible for one proton in one nucleus to change to a neutron and bind or 'fuse' together with the other nucleus. The great force required here includes both extreme heat and extreme pressure, comparable to that inside stars.

The infrared brightness of a star system decreases when a planet goes into eclipse

True because during the eclipse the star blocks the planet's contribution and before the eclipse the systems infrared brightness comes from the star and the planet.

A new orbiter observes a volcanic eruption on Venus.

True, Venus has more volcanoes than any other planet in the solar system

Radiometric dating of rocks brought back from one lunar crater shows it formed only 10mill years ago

True, With no atmosphere, asteroids have collided with the moon and created craters since it was formed 4 billion years ago and will continue to do so as long as it exists.

Drilling into the Martian surface, a robotic spacecraft discovers liquid water a few meters beneath the slopes of a Martian volcano.

True, mars has various evidence of water being both present on the surface and beneath it.

Astronomers discover an asteroid with an orbit suggesting that it will impact earth in the year 2064.

True, this could most definitely happen.

If a distant galaxy has a substantial redshift (as viewed from our galaxy), then anyone living in that galaxy would see a substantial redshift in a spectrum of the Milky Way Galaxy.

True. The increasing distance between the two galaxies will red shift light traveling between them in either direction.

What do we mean by a runaway greenhouse effect? Explain why this process occurred on venus but not on earth.

Venus is closer to the sun. Hotter temp = more evaporation = hotter atmosphere = hotter temp = more evaporation, etc... UV rays would tear away hydrogen atoms, leaving Venus as we know it.

Discuss the geologic activity on Venus and Mars. Are these planets still active and/or volcanic? Why?

Venus is more likely to be geologically active than Mars. Mars cooled down faster, which means the crust gets thicker and volcanoes cannot penetrate, which slows down core spinning. It eventually lost its atmosphere due to this. Venus is able to sustain its greenhouse effect. It has few craters, possibly from resurfacing from volcanism.

Why was Venus' history so different from Earth?

Venus' proximity to the Sun likely made it incapable of keeping liquid water on the surface. The heat evaporated its oceans, which released absorbed CO2 into the atmosphere. Earth is in a "Goldilocks" zone where we are able to sustain liquid water (which absorbs CO2) which gave rise to life and keep a balanced greenhouse effect.

How often should we expect impacts of various sizes on Earth? How serious a threat do we face from these impacts?

Very rare. If we spotted an object that could cause an impact, we'd have a few years to prepare. Unlikely to hit an everything important because of how much of Earth's surface is water. Not a big threat, it is a risk but isn't a .

How can scientists account for the fact that extrasolar planets seem to come in a wider range of types than the planets of our own solar system?

We need to factor in the fact that planets in other systems have hotter or cooler suns, which will change how the planets made of the same material appear in different systems.

Can an asteroid be pure metal?...

Yes, it must have been the core of a shattered asteroid.

In general, what kind of terrestrial planet would you expect to have the thickest lithosphere?

a small planet

How long does it take the star and planet to complete one orbit around their center of mass?

about 4 days

What maximum velocity does the star attain?

about 50 m/s

Which of these groups of particles has the greatest mass? (a) a helium nucleus with two protons and two neutrons (b) four electrons (c) four individual protons

c

The set of spectral lines that we see in a star's spectrum depends on the star's:

chemical composition.

What does Pluto most resemble?..

comet

A star whose spectrum peaks in the infrared is:

cooler than our Sun

Oxygen (O)

eight protons, eight neutrons, eight electrons

What are the four major ways in which light and matter can interact? Give an example of each from everyday life.

emission: a copper wire in a light bulb gets heated and emits photons transmission: a transparent object like window glass transmits the Sunlight into your house absorption: the walls however absorb the light and make a shadow reflection: mirrors

About how often does a 1-kilometer object strike Earth?...

every million years.

Boron (B)

five protons, six neutrons, five electrons

Beryllium (Be)

four protons, five neutrons, four electrons

The fact that we observe neutrinos from the Sun provides direct evidence of

fusion in the Sun's core

How big an object causes a typical shooting star?...

grain of sand or small pebble.

Fluorine (F)

nine protons, ten neutrons, nine electrons

Did a large terrestrial planet ever form in the region of the asteroid belt?

no, because Jupiter prevented one from accreting.

Hydrogen (H)

one proton, one electron

Summarize the roles of planetary size and distance from the sun in explaining the histories of the terrestrial worlds.

only a suitably large terrestrial planet located at an intermediate distance from its star is likely to have conditions under which life could thrive

Jupiter nudges the asteroids through the influence of...

orbital resonance.

Solar energy leaves the core if the Sun in the form of

photons

Which heat source continues to contribute to Earth's internal heat?

radioactive decay

A spectral line that appears at a wavelength of 321 nm in the laboratory appears at a wavelength of 328 nm in the spectrum of a distant object. We say that the object's spectrum is

redshifted

How to find the number of protons and neutrons when given the atomic mass

round atomic mass, then: atomic mass - number of element. Element number is the number of protons. What ever is left is the number of neutrons.

Nitrogen (N)

seven protons, seven neutrons, seven electrons

the term super-Earth means a planet that is

similar in composition to earth but larger in size

Carbon (C)

six protons, six neutrons, six electrons

Which of a planet's fundamental properties has the greatest effect on its level of volcanic and tectonic activity?

size

Neon (Ne)

ten protons, ten neutrons, ten electrons

Relationship between pressure, volume and temperature

the pressure of a gas is inversely related to the volume and directly related to the temperature. If temperature is held constant, the equation is reduced to Boyle's law. Therefore, if you decrease the pressure of a fixed amount of gas, its volume will increase.

Suppose the impact 65 million years ago had not occurred. How do you think our plant would be different?

there would be no mammals since the conditions for the formation of mammals are hard to achieve.

Lithium (Li)

three protons, four neutrons, three electrons