Astrobiology

1. Name and describe the major components of the universe including: stars, solar systems, nebulae, star clusters, galaxies and galaxy clusters.

Star

• ball of hot gas

• mostly hydrogen and helium

• Undergoes nuclear fusion (two hydrogen nuclei merge to form a helium. The process releases energy)

Solar system star +celestial bodies (held by star’s attraction, revolve around it)

Nebulae a giant cloud of dust and gas in space.

Star clusters groups of stars, held by self-gravitation

Galaxies collection of gas, dust, and billions of stars and their solar systems, all held together by gravity.

Galaxy clusters groups of galaxies, held by self-gravitation  

2. Outline the hierarchy of structure in the universe: clusters of galaxies, galaxies, solar systems etc

Superclusters

Galaxy Clusters

Galaxies

Solar Systems

Stars

Planets and Moons

Asteroids and Comets

3. Outline the development of the telescope and its significance to the development of our understanding of the Universe.

• 1608 – Lippershey presented the first telescope to the prince (realised that viewing an object through a convex and concave lens would magnify it if they were placed at just the right distance from one another)

• 1609– Galileo copied the telescope design but used it in the sky 

• Discovered moon wasn’t completely smooth or spherical

• 4 of jupiter's moons

• The phases of Venus

• And more      

• 1663 – James Gregory designed a telescope using a parabolic mirror for a better quality image.

• Isaac Newton Newton designed a smaller and simpler telescope that functioned better the Gregory’s

• 1733 – Chester Hall designed a telescope that used 2 lenses of different refractive indices to unbend chromatic aberration.

• 1770s -1780s – William Hershel made big reflectors.

• 1847 – Lorde Rosse made a large telescope in Ireland. Good technology, not good location.

• 1917 – 254cm Mt Wilson reflector created.

• 1920 – The wide angle problem was solved

• Today astronomers use giant mirrors on remote mountaintops

The development of the telescope was significant because it opened our eyes to the fact that there was a whole universe to discover and understand. Prior to this, most people’s views were more geocentric, meaning we believed that everything revolved around us and the Earth. However, the discovery of the telescope led to a more heliocentric way of thought being adopted. 

4. Identify and outline a typical telescope, detection method and image formed (using a schematic diagram) to provide information about the universe in the visible and radio parts of the EM spectrum.

Most common telescope : Newtonian reflector

Type of reflecting telescope invented by Sir Isaac Newton

Uses a concave primary mirror and flat diagonal secondary mirror (light travels down the telescope, hits the concave mirror and reflects off the concave mirror, travels back toward the front of the telescope, hits the secondary mirror)

5. Use appropriate scales to describe differences in sizes of and distances between structures making up the universe.

1 light year = 9.46 x 10¹² km

1 AU (astronomical unit) = 150 million km (distance from Earth to Sun)

1 parsec (pc) = 3.26 light-years (3.086 × 1013 kilometres)

6. Describe how gravity acts on all objects in the Universe and how these objects move due to gravity.

• acts on all objects in the universe

• causes objects with mass to be attracted to each other, and it is responsible for many of the motions and structures that we observe in the universe.

• makes objects move in certain ways eg. the Moon orbits around the Earth, the Earth orbits around the Sun 

• formation and evolution of galaxies

• As mass increases gravity increases

• As distance increases gravity decreases

7. Qualitatively outline the general features of stars and their types using the HR diagram.

• graph that plots the luminosity (brightness) of stars vs temperature (colour).

• The majority of stars fall on the main sequence, where they spend most of their life burning hydrogen into helium in their cores.

• High-mass stars are larger, hotter, and brighter than low-mass stars.

• Low-mass stars are smaller, cooler, and dimmer than high-mass stars.

• Stars can evolve off the main sequence into different stages such as red giants, white dwarfs, neutron stars or black holes, depending on their mass.

8. Examine the sequence of events in the life cycle of high and low mass stars including the following:

• nebulae

 A star begins as a nebula, a cloud of gas and dust.

• main sequence

In the main sequence stage, a star burns hydrogen into helium in its core, releasing energy and producing light. This stage can last for millions or billions of years, depending on the star's mass.

• red giant

As a star's hydrogen supply dwindles, it begins to burn helium into heavier elements, causing the core to contract and the outer layers to expand. This results in a red giant, a large, cool, and luminous star.

• planetary nebula 

In low to intermediate mass stars, the outer layers of the red giant are expelled into space, forming a planetary nebula.

• Supernova

In high-mass stars, the core contracts to the point where it cannot withstand its own gravity, resulting in a catastrophic explosion known as a supernova.

• white dwarf

Low-mass stars will eventually exhaust their fuel and enter a different pathway. They will shed their outer layers and form a planetary nebula and eventually, the core will collapse into a white dwarf. White dwarfs are small, extremely dense, and hot objects that gradually cool over billions of years.

• neutron star

The remnants of a supernova can form a neutron star, an extremely dense object made up of closely packed neutrons.

• black hole

In very high-mass stars, the remnants of a supernova can form a black hole, a region of space with such strong gravity that nothing, not even light, can escape.

9. Describe how Edwin Hubble radically changed people's view of the universe in his discovery of the recession of distant galaxies.

• Examined spectra of light emitted by distant galaxies

• Noticed redshift, indicating movement away from Earth (Doppler Effect) 

• Greater redshift corresponds to greater velocity Discovered Hubble's Law - evidence of an expanding universe and the Big Bang theory 

• People's views changed from thinking the universe was infinite or limited to the Milky Way 

• Therefore, realising the Big Bang Theory is plausible and the universe is truly expanding.

10. Describe the main features of the big bang model of the evolution of the Universe.

• 13.8 billion years ago the universe as we know it did not exist

• That the universe as we know it today began with a sudden explosion at a single extremely dense point.

• All the matter an energy was initially concentrated into very high energy one point. Over billions of years it’s spread out an cooled.

• As everything settled, all the matter sent out formed stars and planets, the universe as we know it today.

• It has continued to expand ever since

11. Identify the evidence that has led to the acceptance of the big bang model; CMBR, redshift of galaxies and the ratio of elements in the universe.

Redshift of galaxies: 

When we look at different objects in space, the radiation that comes off of them is a longer wavelength than it should be. The red side of the spectrum is the side with longer wavelengths, so basically, waves travelling from distant bodies in space move towards the red side of the light spectrum. The waves are being stretched or spread out before they reach us. This stretching can be explained using the Doppler effect:

“Waves coming from a source which moves away from us will arrive at a lower frequency”

So, if all light from distant stars it being redshifted, then everything in the universe is moving away from us.

It has also been observed that objects further away fro  us are being redshifted more. This shows that things that are further away are moving away at a faster rate. Redshift is a key piece of evidence for this idea of the expanding universe.

Relates somewhat to Doppler effect, it uses different wavelengths and frequencies of light to show if a galaxy is moving away from earth (redshift) or towards earth (blueshift). 

CMBR:The Cosmic Microwave Background (CMB) is the cooled remnant of the first light that could ever travel freely throughout the Universe. This 'fossil' radiation, the furthest that any telescope can see, was released soon after the 'Big Bang'. Scientists consider it as an echo or 'shockwave' of the Big Bang.

Ratio of elements: 

Scientists noticed spread out, weak microwave radio signals coming from everywhere in the universe. This radiation could be explained with the big bang theory. The ideas is that the extreme heat from the sudden explsion at the start of the universe would  result in leftover radiation as the universe spread and cooled. That suggests a large explosion. Additionally, for the radiation to still be observable it mustnt have had enough time to completely dissipate, which suggests that the universe must have had a definitive start date 

Ratio of elements in the universe: 

12. Outline how the big bang model has developed over time through the gathering of evidence and the scientific method.

• The big bang theory was proposed in the 1920s based on observations of the universe, such as the redshift of distant galaxies.

• The discovery of the cosmic microwave background radiation in 1964 provided strong evidence for the big bang theory.

• The observations of the large-scale structure of the universe, including galaxy clusters and voids, also support the big bang theory.

• Scientific methods such as computer simulations and measurements of the universe's expansion rate continue to refine and support the big bang model.

13. Relate features of the big bang theory and scientific evidence to the age of the Universe.

• The big bang theory proposes that the universe began as a singularity, a point of infinite density and temperature, around 13.8 billion years ago.

• Evidence such as the cosmic microwave background radiation, the abundance of light elements, and the expansion of the universe support this age estimation.

• By measuring the cosmic microwave background radiation, scientists can calculate the age of the universe with precision, resulting in an age of 13.8 billion years.

22. Derive relationships and perform calculations using provided equations.

Weight = mass x gravity at Earth’s surface (9.8 m/s)

W = mg 

Newton’s Universal Law of Gravity

m₁m₂

F = G  

  d₂

F = force of attraction/gravity (N)

G = gravitational constant (6.67 x 10^-11)

m₁ = mass of object 1 (kg)

m₂ = mass of object 2 (kg)

d₂ = distance between centres of two masses (metres)

23. Use appropriate scientific notation, significant figures and SI units in calculations and when arranging data.

SI units

Length –metre

Mass – kilogram

Time – seconds

24. Assess the accuracy, validity and reliability of an investigation.

Validity

A valid experiment is a fair test. If an experiment is valid:

• It investigates what you think it will 

• It incorporates suitable equipment

• Variables are controlled

• Appropriate measuring procedures are include
  

Reliability

A reliable experiment has results that can be obtained consistently. To ensure results are reliable

• The experiment must be repeated and consistent results obtained (with an acceptable margin of error)

• Use the most appropriate measuring instrument correctly, for example, avoiding parallax error

Accuracy

Accuracy depends on the design of the experiment (ie the validity of the method) and the sensitivity of the instrument used. Results are accurate if 

• close to true value of the quantity being measured

• Supported by secondary sources

• calculations done correctly w. appropriate sig figs

• using correct values for constants 

• % error less than 5%
  

26. Calculate the slope/gradient of a straight line of best fit and use it in further calculations.

m = rise / run