Flashcards in Astronomy Third-Fourth Test Deck (63)
Rocky body flying through the solar system
Fireball falling through Earth's atmosphere. have radiant point, shower ones named after constellation they come from (leonids, perseids, etc) Both shower and sporadic types
meteoroid that has survived meteor status and landed on earth's atmosphere. falls vs finds, always sporadics.
meteorite impacts on earth.
Ranging from small rocks that bust through cars and houses to massive rocks that break up in atmosphere and cause events like Tunguska in 1908, Vladivostok in 1947, and Cheybalinsk (17m across) in 201(2). No human has even been killed by one.
Formerly called Barringer Crater. Impact crater in Arizona, not much weathered because Arizona. 1 mile across. Owned for a time by a rancher who tried to mine nickel from it. Once a passenger plane flew into it and couldn't get out. Today, tourist destination.
Streams of charged particles (p+ and e- mostly) coming from sun, through empty interplanetary space. Interacts with magnetic fields and things throughout the solar system
Magnetic field lines around a planet cause charged particles (ie solar wind) to be directed towards the poles of a planet. These excite air molecules around poles, causing them to glow. Seen as green bands in sky, sometimes other colors. Once every 100 yrs in texas, 2-3x a year in VT, ALL THE TIME in northern canada. Can happen on any planet with mag field and atmosphere. borealis=N, australis=S.
ALHodsifjaoi, blasted off of Mars on impact, apparently greater than EV. Has life in it maybe?
Murchison asteroid from 1969 has amino acids.
Meteoroids in space
Rocky debris left over from comets. Showers when earth's orbit crosses theirs.
corona of sun
outer layer of sun, really really hot (unknown why) but very not dense. flares from here sometimes due to magnetic fields crashing through surface. Coronal mass ejections send waves of charges particles at earth.
11/22 year cycle of maximum and minimum solar activity, including number of sunspots. 11 years between maximum, but each maximum magnetic field flips and regrows.
stream of charged particles e- and p+ flying from sun. wind is not net charged. magnetic fields of bodies directs them to poles, causing excitation of atmosphere and arorae. dangerous space radiation for astronauts.
borealis in north and australis in south.
addition and subtraction of velocity. for example A going 90MPH south, B going 30 MPH north, C stationary. A sees B as 60mph, c sees him at 90mph. EVERYTHING IS RELATIVE, THERE IS NO ABSOLUTE FRAME OF REFERENCE.
planes and galilean xformation
Plane traveling left at 400mph, A traveling left at 300, b right at 100. A sees it at 300, because it "already has" some of the speed. B sees plane traveling at IDK
posited explanation for light in 1800s. If sound waves and water waves have a medium, so must light! It is found everywhere light permeates, excluding opaque materials. invisible to the senses. Earth revolving around sun MUST travel through it- does it drag, slipstream, around it?
disproved aether theory. used split and recombined beams of light expected to show one beam slowed down as it moved through the aether. It didn't however, showing that light does not experience galilean transformation. expected light from behind us to have to "catch up" a la the planes above. Didn't happen.
how to account for light speed invariance
think of velocity as a change in position in space-time. space time varies with frame of reference, the dimensions of space-time are flexible depending on point of reference.
published by einstein in 1905. wasn't first to say it. said space and time can shrink, grow and bend. works only for non-accelerating fields.
Principles of special relativity
1. The laws of physics are the same for all inertial frames of reference
2. The velocity of light is the same for all observers
background of relatvity
Math worked out by Heinrich Lorentz, based on equations of James Clerk Maxwell that completely described EM fields.
changes of space-time at relativistic speeds
as an object moves faster towards speed of light, its length contracts, time passes more slowly than it, mass approaches infinity. these values become nonsensical for speed of light and beyond.
works because faster twin SLOWS DOWN (outside special relativity) and returns to slower, earth frame of reference
frame of reference
an individual view of reality. THERE IS NO CORECT ONE. based on the speed of the body you are traveling on, in, for example in a car, on earth, running.
relativistic guy and skiw guy look at each other
both see each other as shorter, living, heavier. not a paradox because you can only be in one frame of reference at a time.
outside of special relativity, part of general. is absolute, seen as the same from all frames of reference.
L'=Lo sq [1-v^2/c^2]. same with V' and M'
Mathematically describes the relativistic transformation of something. If V is very high, close to c, the prime value is much smaller than the base.
1/ sq[1-v^2/c^2] Just have no clue what this is
other lorentz stuff.
can do above lorentz transformation for length, time and mass. if the same mass applies to all of these- they must be the same thing. Leads to the conclusion that space = time and that E=mc^2.