Astr Final Cheat Sheets (1)

(diagram shows the rota/on curve for the Milky Way. 1 km/s = 1000 m/s) 1 ly = 9.46 x 1015m. mass of the Sun = 2 x 1030kg. 1 x 10^11 Msun (diagram shows the rota/on curve for the Milky Way. 1 km/s = 1000 m/s) From the Sun, the distance to the Galac/c Center is about 8,000 pc 1.4x10 9 m? -26.7 -1.5 magnitude Sirius appears 25x brighter than second magnitude Polaris T A blue star has a higher surface temperature than a red star. T A blue star with a peak wavelength in the UV has a higher surface temp than a red star with a peak wavelength in the IR T According to the universal law of gravita/on, if you double the masses of both aVrac/ng objects, then the gravita/onal force between them will - increase by a factor of 4. According to Newton's second law (F=ma), if you double the force ac/ng on a body, the accelera/on will double True A main sequence star has an absolute magnitude of 2. What would be the approx. luminosity of the star and what would be the spectra class? – 13.5 Lsun; spectral class A A planet or comet will speed up as approaching the sun? True A skater can spin faster by pulling her arms closer to her body or spin slower by spreading her arms out from her body. Assume a skater pulls her arms in and her speed increases by a factor of 3. What can be said to be true. The radius of spin decreased by a factor of 3. A solar mass star will evolve off the main sequence when It builds up a core of inert helium A television adver/sement claiming that a product is light years…… it uses “light years” to talk about Lme, but a light-year is a unit of distance A type B9 star is hoVer than a type A0 T According to Wein's law, the wavelength of the peak energy will be ________ if the temperature of the blackbody is doubled . - halved According to Hubble's Law, the greater a galaxy's redshib,the farther it is from us According to Newton’s law of universal graviatoin, if the M were 6x further from E, the force by E on the M would decrease by a factor of 36 According to the Hubble Law graph shown, a galaxy cluster with a recessional velocity of 25,000 km/s will be 400 million pcs away According to the inverse square law of light, how will the apparent brightness of an object change if its stance to us triples? Its apparent brightness will decrease by a factor of 9 According to Wein’s law, the higher the surface temperature of a star,the redder its color F According to Wein’s Law if the surface temp is increased by a factor of 6 its peak wavelength will decrease by a factor of 6 According to Wein's law, the wavelength of the peak energy will be ________ if the temperature of the blackbody is doubled. : Halved According to the universal law of gravita/on, if you double the masses of both aVrac/ng objects: then the gravitaLonal force between them will increase by a factor of 4 A circular orbit would have an eccentricity of 0 A comp accessory salesman aVempts to convince Neutrinos rarely if ever interact with your computer Aber a massive-star supernova, what is leb behind? either a neutron star or a black hole Aber a supernova event, what is leb behind? either a neutron star or a black hole A high-mass star dies more violently than a low-mass star because it generates more heat a liTle over a million All but one of the following statements describe why scien/sts doubt the solar sunspot cycle affect global climate Solar winds can affect satellite communicaLon All neutron stars are pulsars, but not all pulsars are neutron stars. F All of the following statements are true. Which one explains the reason why there is not a solar eclipse at every new moon? The orbital plane of the m is Llted by 5 all others All radio telescopes are reflectors in design T All stars spend approximately the same amount of /me on the main sequence F All stars that become supernovae will leave behind a neutron star F All the following statements are true. Which one explains the reason that there is not a solar eclipse at every new Moon? The orbital plane of the moon is Llted slightly (about 5 degrees) to the eclipLc plane A loop of gas and charged par/cles following the mag field lines between sunspots poles is a prominence/filament Although it is difficult to tell from our vantage point inside the galaxy, MW spiral T A main sequence star of 8 solar masses will be approx. 4000x more luminous than the Sun. T ? and its core eventually collapses very suddenly? An O-star has a hoVer surface temp than the S, Therefore compared to the S its emission peaks in the blue part of the spectrum A par/cular nebula is a hot, thin cloud of glowing gas, so its emission spectrum looks like f=8.9x10^14hz and E=5.9x10^-19J A par/cular star has an absolute magnitude of M=-0.3. Determine the lum… Spica A par/cular star has an angle of parallax of 0.1 arcsecs. What is the distance about 33 ly A par/cular star in a binary star systems orbits the other with an average orbital radius of 3AU and a period of 5 yrs. What is the sum of the masses of the 2 radius 1.1 A planet (or comet) will speed up as it approaches the Sun T A planet whose distance from the Sun is 5 AU would have an orbital period of how many Earth-years? √125 A planet whose distance from the S is 3 A.U orbital period = √ 27 A planet whose distance from the Sun is 18 AU orbital period = 76 Apparent magnitude is a measure of a star’s brightness, as seen form Earth. apparent magnitude is m=3.75. 224 pc Approximately how far is the Sun from the center of the galaxy? 27,000 light-years A protostar moves onto the main sequence with a mass of 0.18 solar masses. the luminosity of the star and hence its spectral type. M A protostar moves onto the main sequence with a mass of 3.2 (or 5.6) solar masses. the luminosty of the star and hence its spectral type. B A protostar moves onto the main sequence with a mass of 3.2 solar masses B A protostar of 50 solar masses will probably turn into a type O main sequence star. T A protostar of 50 solar masses will probably turn into a type O main sequence star T A pulsa/ng variable star w/period of 10d would be a Cepheid hve abs mag of -4.2 T A pulsa/ng variable star w/period of 50d would be a Cepheid hve ab smag of -6.3 T A radio telescope (collects radio light waves) and an op/cal telescope (collects visible light) of the same size have the same angular resolu/on F A radio telescope and an op/cal telescope of the same size have the same D F around Earth. As a star begins to evolve away from the main sequence, it gets larger T A sidereal year is defined as the Lme it takes for Earth to complete an orbit around the Sun. As it moves in its orbit, Earth is always exactly 1AU from the Sun F A solar eclipse can occur only when the Moon is new. T A solar eclipse can only occur when the Moon is new T As originally stated, the Copernican model did no beVer a job of predic/ng planetary behavior than did the Ptolemaic one. Hence neither model could be “disproved” T Assume that in the future, a telescope is built on Europa and measures a parallax of 1.3” Procyon lies about 13 light years distant. What must be the baseline 5.2AU A star (no maVer what its mass) spends most of its life: as a main sequence star A star has an absolute magnitude of -6 and an apparent magnitude of +12. What is the distance to the star? 40,000pc A star has an apparent magnitude of 3 and an absolute magnitude of -1. Determine the distance to the star. – 63 parsec A star has an apparent magnitude of +7 and an absolute magnitude of -4. What is the distance to the star? 1585 pc A star has a space velocity of 15 km/sec and a transverse velocity of 12 km/ sec….redshibed… The radial velocity is 9 km/s away from Earth A star is on the horizontal branch of the H-R diagram.true? burning both hydrogen& helium A star of ½ sun’s diameter, but twice as hot, would be 4x more luminous than the sun T A star of apparent magnitude +5 appears fainter than a star of apparent magnitude +3 A star of ten solar masses would probably stay stable on the main sequence only about 1/1000th as long as our Sun. T A star of ten solar masses would probably stay stale on the main sequence only about 1/1000th as long as our Sun T A star of the Sun's diameter, but three /mes as hot, must be 81X more luminous than the Sun. T A star of the Sun's diameter, but twice as hot, must be 16X more luminous than T A star of the S’s diameter but 5x hoVer must be 625x more luminous than the S F A star’s abs mag and its app mag have the same numerical value. How far is this star 10pc A star with a parallax angle of 0.05" is – 20 parsec away. Aprox 3.24x more As the sun evolves into a red giant in the distant future with a surface temp of about 2000K, its peak on the Planck curve will move into the infrared A supernova occurred 10,000 years from now in a galaxy 50,000 light years away will be observed on earth 40,000 years from now A supernova that occurred 30,000 years ago in a galaxy 100,000 light years away will be observed on Earth 70,000y from now A supernova occurred 60,000 years ago in a galaxy 20,000 light years away. When was/ will be the event observed on Earth? 40,000 years ago As we look at larger scales in the universe, we find a larger and larger percentage of the maTer is dark At apogee the moon is at its farthest from earth and thus appears smaller than normal. Because of this it has the smallest angular size in the sky at this /me. T A telescope with a 600 mm objec/ve lens collects how many /mes as much light as does your eye's 6 mm exit pupil? 10,000X

At perigee the moon is at its closest from earth and thus appears larger than normal and is moving fastest in its orbit around earth T At the distance of Jupiter (6 /mes further away from the Sun than Earth) the amount of sunlight received per square cen/meter is different by what factor? 36 Lmes less At the distance of Jupiter the amount of sunlight received per square cen/meter different by what factor: 12 Lmes less At very large distances from the Sun, its corona turns in to the solar wind. T At which of these Kelvin temp would a blackbody radiate400-700nm 6000K A type A9I star is the same temperature as a type A9V star. T A year is defined as the Lme it takes for Earth to complete an orbit around the Sun Based on current es/mates of the value of Hubble's constant, how old is the universe? 12-16 billion years old Because they all involve the detona/on of a carbon-rich white dwarf at Chandrasekhar's limit, all type I supernovae are equally luminous and hence are excellent standard candles. T Betelgeuse is the bright red star represen/ng the leb should of the constella/on Orion. All the following statements about B are true. Which one can you infer from its red color? The peak intensity of radiaLon is likely in the IR range. By approximately how many x dimmer is the star Sirius (m=-1.7) than the full Moon (m=-13) in our sky? 33,000x dimmer By what mechanism does solar energy reach the Sun's photosphere from the layer just Calculate the diffrac/on limit if the Hubble Space Telescope is using a green filter of 556nm and has a diameter of 10 meters 0.014 arcsec Careful measurements reveal that a star maintains a steady app brightness at most /mes expect that a precise interval of 127 the star is a member of eclipsing Colors appear different to us because of their photons' different: frequencies Compared to a cluster containing type O and B stars, a cluster with only type F&cooler stars will be older Compared to the star it evolved from, a red giant is cooler and brighter Compared with our sun, most stars in the halo are: Old, red and dim and have fewer heavy elements. Compared with stars in the disk, orbits of stars in the halo are ellipLcal, with random orientaLon Consider HR diagram ONE on the cover sheet. Find Capella and the Sun. Es/mate how many /mes bigger or smaller Capella than Sun between 9 and 10x bigger Consider the HR diagram on the cover sheet of the exam, which of the following lists if the correct sequence of stars in order of increasing intrinsic brightness Procyon B, Sirius B, the sun, Deneb Consider the image below which shoes the top of the convec/on zone….If one par/cular spectral line has a rest wavelength of 480.00 nm, what is the measured wavelength of the same line from the diagram? 480.48 nm Consider the images below which shows the top of the convec/on zone of the Sun. The paVern of rising hot gas cells all over the photosphere is called sunspots Consider the HR diagram shown here. What would be the likely classifica/on of star B: G8III Consider this diagram, which statement is true, updown4, lebright6 the wavelength is 6 Consider this diagram. Which statement is true? The amplitude is 4. Constella/ons are close clusters of stars, all at about the same distance from the Sun. F Constella/ons are close clusters of stars, all at about the same distance from the Sun. F Constella/ons r close clusters of stars all at about the same distance fromS F Copernicus’s S centered model of the SS gave much beVer predic/ons than Ptolemy F Degeneracy pressure is the source of the pressure that stops the crush of gravity in all the following except a very massive main-sequence star. Detailed measurements of the disk and central bulge region. According to Hubble's classifica/on, the Milky Way would most likely be classified as SBb Detailed measurements of the disk and central bulge region of our Galaxy suggest our Milky Way is a barred spiral galaxy detec/on of neutron stars has been compared to observing a lighthouse. in the lighthouse model, the star literally turns on and off like a lighthouse beacon Determine the eccentricity of this ellipse if one of the foci is at x=2 0.4 Determine (calculate) the Hubble class for this ellip/cal galaxy.I have approx. outlined the galaxy with an ellipse and a ruler is provided. E3 Determine the orbital period of Neptune if the syno/c period is 1.00616 years. 164 yrs Determine the orbital period of Uranus if the syno/c period is 1.013 yrs 84 yrs Doubling the distance between 2 objects halves the gravita/onal force btw F During the Hydrogen shell burning phase: The star grows more luminous Dr. Smith believes H0 =70 km/s/Mpc. Dr. Jones believes H0 = 50 km/s/Mpc. Dr. Smith believes that the universe is younger than Dr. Jones believes. Dr. X believes that the Hubble constant is H0 = 55 km/s/Mpc. Dr. Y believes it is H0 = 80 km/s/Mpc. Dr. X believes that the universe is older than Dr. Y believes. During the period each year when we see Mars undergoing apparent retrograde mo/on in our sky, what is really going on in space? Earth is catching up with and passing by Mars in their respecLve orbits. Each choice below lists a spectral type and luminosity class for a star. Which one is a redgiant? Spectral type m2 , luminosity class I Earth is always precisely 1AU from the Sun all year around F Energy from the core of the S first travels slowly through a convec/on zone and then much faster through the outer radia/on zone. F Energy from the core of the Sun first travels slowly through the convec/on zone and then much faster through the radia/on zone F Eventually, all low mass stars will become white, then black, dwarfs. T Every red dwarf star (M<0.01MSun) that ever joined the main sequence is s/ll there today T Every second, the Sun converts about 600 million tons of hydrogen in 596 million tons of helium. the remaining 4 million tons of mass is converted to an amount of energy=4 million tons Lmes the speed of light squared Everything looks red through a red filter because the filter transmits red light and absorbs Except for hydrogen and most of the helium, all the elements have been formed through stellar nucleosynthesis. F For a nova or a Type 1a Supernova to occur, the system must have already been a mass- transfer binary For a star of 10 solar masses, its main sequence life span will be only 1/1000th of the sun For our Sun, the produc/on of carbon will be the end of its nucleosynthesis T For this ques/on, see the parallax equa/on on the coversheet for the baseline of Pluto’s orbit. The semimajor axis of Pluto’s orbit is 40AU,0001arcsec 40,000 pc From Earth, the S and M have about the same ang distance. Hence, during a solar eclipse the M just barely blocks the sun’s disc allowing for the outer atmosphere of the sun to be observed T From hoVest to coolest, the order of the spectral types of stars is - OBAFGKM . From Kepler's third law, a hypothe/cal planet that is twice as far from the Sun as Earth should have a period of more than 2 Earth years. From Kepler 3 rd law, an asteroid with an orbital of 8 yrs 4 astronomical units From laboratory measurements, we know that a par/cular spectral line formed by hydrogen appears at a wavelength of 121.6 nanometers (nm). The spectrum of a par/cular star shows the same hydrogen line appearing at a wavelength of 121.8 nm. What can we conclude? The star is moving away from us at about 500 km/s. From laboratory measurements, we know that a par/cular spectral line formed by hydrogen appears at a wavelength of 121.6 nanometers (nm). The spectrum of a par/cular star shows the same hydrogen line appearing at a wavelength of 122.8 nm. What can we conclude?- the star is moving away from us at approx 3000 km/s From the center outward, which of the following lists the "layers" of the Sun in the correct order core, radiaLon zone, convecLon zone, photosphere, chromosphere, corona Galaxies look the same whether viewed in visible or X-ray wavelengths. F Galileo's observa/ons of the en/re phase cycle of Venus, of the moons of Jupiter, of the scarred surfaces of the Moon, of Sunspots on the Sun, etc. all were crucial pieces of evidence that helped solidify the Copernican Revolu/on. T Galileo observed the phenomenon of solar rota/on in the early 1600s measuring the moLon of sunspots across the solar surface Galileo’s observa/ons of sunspots proved the Sun was rota/ng, like the Earth. T Gamma Rays are a type of electromagne/c radia/on produced in stars. T Given: the planets orbi/ng the nearby star 51 Pegasi, 20x, 400x, M=5.98 x 10^24, R= 6.37x 10^6 , weight = the same as you do here Granula/on is the most obvious proof of solar convec/ve energy transport. T Granula/on is the most obvious proof of solar convec/ve energy transport T Grass (that is healthy) looks green bc it reflects green light and absorbs other colors Grass is green because it absorbs green light, reflec/ng all other colors F Green light has a shorter wavelength than orange light. In a 5 inch Newtonian Reflector Telescope, green light will: provide beTer angular resoluLon than orange light Halving the distance between two objects doubles the gravita/onal force between them False Harlow Shapley concluded that the sun was not in the center of the milky way galaxy by mapping the distribuLon of globular clusters in the galaxy have a period of more than 2 yrs HenrieVa LeaviV first showed the rela/onship between the mass and luminosity of Cepheids and their period of pulsa/on; the brighter, the longer this period. T HenrieVa Swan LeaviV first showed the rela/onship between the mass and T history of the universe than Galaxy 2 How are the event horizon and Schwarzschild radius related? The Schwarzschild radius is equal to the distance from the singularity of a black hole to the event horizon. How are wavelength, frequency, and energy related for photons of light? Longer wavelength means lower frequency and lower energy.

How much stronger is the gravita/onal pull of the Sun on Earth, at 1 AU, than it is on Saturn at 10 AU? 100X How much stronger is the gravita/onal pull of the Sun on Earth, at 1 AU, than it would be if Earth were at 10 AU 100X How can we characterize the rota/on of the S? differenLal rotaLon with the equator rotaLng faster than the poles. How did Edwin Hubble measure the distance to the Andromeda Galaxy? He applied the period-luminosity relaLon to Cepheid variables How did the Ptolemaic model explain the apparent retrograde mo/on of the planets? It held that the planets moved along small circles that moved on larger circles around earth How does the light-collec/ng area of an 8-meter telescope compare to that of a 2-meter telescope? The 8 meter telescope has 16 Lmes the light-collecLng area of the 2-meter telescope How do we know that halo stars are older, on average, then disk stars? There are no Blue halo stars how is the sunspot cycle directly relevant to us here on earth? coronal mass ejecLons and other acLvity associated with the sunspot cycle can disrupt radio How long does the Sunspots cycle last on average? About 11 years How long is the precession cycle? 26000 years How many stars could you see with your naked eye on a clear, moonless night from a dark loca/on? A few Thousand How many planet Earths could fit inside the Sun? Rsun=109REarth about 5 million How many planet Earths could fit inside the Sun?v=4/3πR^3 diameter=109 Earth dia a liTle over a million How was Edwin Hubble able to use his discovery of a Cepheid in Andromeda to prove that the “spiral nebulae” were actually en/re galaxies? from the period-luminosity relaLon for cepheid How would you expect a star that formed recently in the disk of the galaxy to differ from one that formed early in the history of the disk? It should have a higher frzcLon of elements heavier than hydrogen and helium Hydrosta/c equilibrium in our Sun is the balance between gravitaLon and pressure If a material is highly opaque, then it absorbs most light If a source of light is approaching us at 3000 km/sec, then all waves blue shiped by 1% If a star has a parallax of 0.05°, then its distance in light years is about 65 light years If a star were moved 10 /mes farther away, its abs mag would drop 5 magnitudes. T If a wave’s frequency doubles, its wavelength is halved If Star A is closer to us than Star B,then Star A’s parall angle is larger than that of Star B If the distance between us and a star is doubled, the apparent brightness is decreased by a factor of four. T If the distance between us and a star is increased by a factor of 5, the apparent brightness is decreased by a factor of 25. T If the Hubble Constant is 70 km/sec/Mpc, the accelera/ng universe is about 5 billion years old. F If the rest wavelength of a certain spectral line is 600nm, but we observe it at 700nm/ 594nm then the source is moving away form us at 50,000/the source is approaching us at 1% of the speed of light If the S-E separa/on was 10AU instead of 1AU what would the flux of sunlight 100x less If the source of light is approaching us at 3,000km/s, then all waves blue shiped by 1% If the star rises about 9PM 2nite and with the sidereal day being 4mins less T If the sun were replaced by a one solar mass black hole we would sLll orbit it in a period of one year If the temp of the solar surface is 5800K and Wien’s law for the peak t=2.9X10^6 500nm If we have a new Moon today, when we will have the next full moon? In about 2 weeks If we observe one edge of a star to be redshibed and the oppoite edge to be blue shibed what can we conclude about the star? The star is rotaLng If you are in the Moon's umbral shadow, then you will witness a total solar eclipse Improvements in tech will eventually allow the en/re electromagne/c F In 1924, Edwin Hubble proved that the Andromeda Galaxy lay far behind the bounds of the milky way...how was he able to prove this? He proved this by observing individual Chepheid variable stars in Andromeda and applying the period-luminosity relaLon. In a binary system, the less massive star always remain farther from the center of mass T In a binary system, the more massive stars always stay closer to the center of mass and move slower T In addi/on to the condi/ons required for any solar eclipse what must also be true to observe a total solar eclipse? The moon’s umbra must touch the area In a spectroscopic binary, if a pair shows a combined set of lines tonight, but a max split of two nights later, its orbital period must be 4days In a spectroscopic binary system, one star shows a large blue shib and the other is showing a small redshib. What conclusion can be drawn from this informa/on? The less massive star is approaching us at this moment In a spectroscopic binary, the star whose lines shib the most weighs the most. F In a spectroscopic binary system, the star showing the larger blue shib is less massive and approaching us at this moment In astronomy, an interferometer can be used to improve the angular resoluLon of radio telescopes In class we modeled the solar system using a yellow ball for the Sun (1 to 10 billion scale). On this scale, it would take about 10 - 15 minutes to walk from the Sun to the inner edge of the Kuiper Belt (Pluto). For reference the distance from the Earth the Sun is 1 AU and the distance to Pluto is about 70 AU. True In order to turn a star’s proper mo/on into its space velocity, we must also know: its distance and radial velocity In the HR diagram on the cover sheet of the exam, which is correct sequence of increasing temperature? Sun, Procyon b, Deneb, Sirius B In the lighthouse model: If the beam sweeps across us, we will detect a pulse of radiaLon. In the previous ques/on one star is exhibi/ng a blue shib, the other is exhibi/ng a redshib (has a picture) . 4:1, 4:1, 8, 20 AU 158 years In the proton-proton cycle, .007 of the mass ends up as energy, with the remaining mass ul/mately becoming helium. T In the proton-proton cycle, 0.007% of the mass ends up as energy, not helium T In the proton-proton cycle, the helium atom and neutrino have less mass than the original hydrogen. What happens to the “lost” mass it is converted to energy In the proton-proton cycle, you must first make deuterium then helium T In the sobball model of the ss it would take a few minutes 2 walk from the T In what range of masses are most stars found? .1 to 100 solar masses It is diffrac/on that limits the resoluLon of a telescopes objec/ve It is impossible to tell the difference between the two types of supernovae. False It is much easier to build large reflec/ng telescopes than large refrac/ng T It is now believed the majority of mass for most galaxies lies in their dark halos. T It is possible to view the M in first-quarter phase the same day as a total F It the radius of a body were doubled, its gravita/onal pull would become 4X stronger. F It took 2 centuries for the Copernican model to replace Ptolemaic model bc there was no scienLfic evidence to support either model 5 It took two centuries for the Copernican model to replaced the Ptolemaic model b/c there was no scienLfic evidence to support either model unLl galileo made his observaLons It was the distribu/on of globular clusters that showed Harlow Shapley we were no Johannes Kepler analyzed data gathered by Tycho and discovered that the T Jupiter is 300x more massive than earth. How much stronger is the gravita/onal pull of the sun on earth at 1au than it is on jupiter at 5au? 12x Kepler’s 1 law worked where Copernicu’ original heliocentric model failed bc ellipLcal, not circular Kepler’s 2 nd law implies what about planetary mo/on? A planet moves faster when closer to the sun Kepler’s 3 rd law, p2=a3 means that all the above are correct Kepler’s first law worked, where Copernicus’ original heliocentric model failed, because Kepler described the orbits as ellipLcal, not circular Light leaving a point source spreads out so that the app brightness b of light per unit area varies with distance d according to which of the following laws b ∞ 1/d^2 Lines of a par/cular element appear at the same wavelength in both emissi T Locate Procyon A on HR diagram 3 of the cover sheet. Es/ma/ng the surface temperature, determine the peak wavelength of radia/on coming from the surface if this star- 29nm Locate Rigel and Betelgeuse on HR Diagram 1 on the cover sheet. Both stars have approximately the same luminosity, but different temperatures. Apply the Stefan- Boltsmann rela/on to es/mate how many /mes bigger Betelguese is than Rigel. Approximately 45 Lmes larger. Locate Regulus on the HR diagram on the cover sheet and es/mate the luminosity rela/ve to the S. if the surface temp of Regulis 12,500k, 5800k, 2.2Rsun Low mass stars should produce white dwarfs, while high mass star will produce more compact and dense end product s T Lunar eclipses are more commonly seen than solar eclipses T Massive, more luminous stars have shorter lives than their smaller, dimmer counterparts. True Mass transfer in binaries occurs when one giant swells to reach the Roche Lobe Mean temperature in Europe during the Maunder min when virtually no lower than avg Mercury, with a higher eccentricity orbit, should change its orbital speed more than do Venus or Earth T Mercury, with a higher eccentricity orbit, should change its orbital speed as a percent more than do low eccen/city Venus or Earth True Modern astronomers have observed the complete life cycle for many stars, making stellar evolu/on one of the best-tested astronomical theories.: False Most of the current star forma/on in the Milky Way occurs in spiral arms T Most stars are born in clusters containing hundreds to thousands of stars T