solar systems

Monday march 3rd:

Clues about the solar system: 

Planetary system 

Nebular hypothesis of the solar system's formation

• A rotating cloud of interstellar gas gradually collapses and flattens to form a disk

• Sun forms at the center and planets form from the disk

• Conceived by a philosopher (kant) and astronomer (laplace) in the 1700s

Nebular hypothesis evidence:meteorites

• Meteorites: (material left over from the young solar system) contain hints to the solar system's formation as well

• Many are mixtures of smaller rocks or pebbles, suggesting formation though  process of aggregation

• An interstellar cloud collapsed to form the sun and a disk of swirling gas and dust aggregates to form planets and moons

Planetary systems are common

• Disks are commonly seen around young stars

• This suggests that planets regularly form around other sats

• An extrasolar planet  is a body with a mass less than13 jupiter masses that orbits a star other than the sun ( objects greater than this are classified as brown dwarfs or stars)

Proto systems

• Evidence abounds of newly formed planetary systems

• 30 systems forming in the orion nebula 

Extrasolar planets

• Over 4,00 of them have been confirmed since 1995

• There are several techniques used to find them:

  • Radial velocity method: as a planet orbits its star, its gravity tugs on the star slightly, creating a doppler shift in the star's spectrum:blue shifted when tugged toward earth, red shifted when tigged away from earth

    • The wobble is detectable with telescopes

    • Jupiter causes the sun to wobble with 12m/s earth causes a wobble of 0.09m/s

  • Transmit method:a planet passing in front of a star (transiting) can decrease the total brightness of the star

    • Far away observes of our solar system would see the sun's brightness drop by 0.009 percent when the earth transited

  • Microlensing method

  • Direct imaging

  • Astrometry 

March 5th: 

Formation of the accretion disks

Material rains down from the collapsing rotating cloud, the vertical motion of material from above cancels the vertical motion from below… but the rational motion remains. The material joins the rotating accretion disk

Energy flow: gravitational potential energy-> kinetic energy->thermal energy

Leftover debris that does not become planets and ect: become comets and asteroids 

Extrasolar planets cont:

Gravitational lensing-microlensing - as the planet passes in front of a star, the starlight can be focused by gravity, temporarily “brightening” the star

Directimaging: block out central part of the star to see the backgrounds 

Exoplanet types: 

Terrestrial: earth sized or smaller, mostly made of rock and metal. Some could possess oceans of atmospheres and perhaps other signs of habitually

Neptune-like:

Similar in size to our own neptune and uranus with hydrogen or helium dominated atmospheres. Minineptuens not found in solar system are smaller than neptune but larger than earth

Super earth:

Typically terrestrial or rocks and more massive than earth but lighter than neptune they might or might not have atmospheres

Gas giants

Size of saturn or jupiter or larger they influence hot jupiters scorching planets n close orbits about the sun

Friday march 7th:

Comet: C/2023 A3 tsuchinshan-atlas

How can I see it?

• Comet will initially appear low on the western horizon in the glow of twilight aout 45 minutes after sunset on each day starting saturday oct 12 through the end of the month

• The comet can be seen without special equipment bit the best view will be through a pair of binoculars

Saturn

• Between sunday evening and monday for the americas the waxing gibbous moon creeps eastward past saturn in the evening sky

Comparative planetology

• The act of comparing common properties across the planets: size, mass temp density period orbital parameters features atmospheres gravity ect.

• Explanation and for similarities and differences must be consistent

• You should be able to relative feature of the planets compare to each other, venus is bigger than mars but smaller than earth

Impact and craters

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Asteroids:

• They are left over debris from the formation of the solar system

• Can vary in composition: stony, carbonaceous, and metallic

• Usually over 100 meters in diameters can be miles across

• Most found in asteroid belt between mars and jupiter

• Total mass of asteroid belt is less than 5% of the mass of the moon 

• They are minor planets, especially those in the inner solar state. The larger ones also have been called planetoids, there's terms have historically been applies to any astronomical object orbiting the sun that did not show the disc of a planet and was not observed to have the characteristics of an active comet

• Not to be confused with dwarf planets 

Meteorites:

• Meteorites are leftover debris from comets or asteroids collisions

• They can vary in composition: stony carbonaceous and metallic

• Usually under 100 meters in diameter

• They are often scattered across the solar system

• Meteors are meteoroids that burn up in the atmosphere

• Meteorites are meteors that survive the trip through the earth's atmosphere

• A meteors needs to be bigger than a softball to survive the trip 

Giant impacts reshape planets

• Effects

• Mercury- missing lighter elements

• Venus-retrograde motion

• Mars-difference between northern and southern hemisphere, earth and other inner plant-gasses water organic compounds

• Earth- we have a moon 

Ideas for the origin of the moon:

• Fission theory: the moon was once part of earth, but somehow separated from it early in their history

  • The samples returned from the moon are missing key volatile elements but match the others each element ratio, most likely the parent body would split into more equal parts

• The sister through- the moon formed together with earth as we believe many moons of the outer planets formed

  • Same with the first half fission theory

• The capture theory: the moon formed elsewhere in the solar system and was captured by earth 

  • An object the size of the moon wandering through the solar system to be captured by the earth is highly improbable

Current accepted theory: giant impact hypothesis

• The earth was impacted by a mars size body

• The impact ejected the material that eventually becomes the moon

Radioactivity and dating (radiometric dating)

• Many isotope can used to determine to age of rocks

  • Uranium to lead 1 mil-4.5 billion 

  • Rubidium to strontium 60 mil-4.5 billion years

  • Potassium to argon 10,000-3 billion years

• Carbon dating can be used to determine the age of organic things from 500-60,000 years 

Radioactive decay: graph shows the amount of radioactive sample that remains after several halflives have passed. After one half life half the samples are left, after 2 half lives one half of the remainder is left, after 3 one half of that is. In reality the decay of radioactive elements in a rock sample would not cause any visible change in the appearance of the rock; the splashes of collar are shown here for conceptual purposes only