· web viewmr. davisastronomy: 2018 final

Mr. Davis Astronomy: 2018 Final Review

I. Our View of the Universe

1. What is astrology:____The belief that the stars influence our lives_______________

2. Which model of the universe assumes that the Earth is at the center?

Geocentric:________Earth Center______________________

Heliocentric:_______Sun Center___________________________________________

3. Dead Greek Guys

Eratosthenes:_____Measured circumference________________________________________

Ptolemy:_________Geocentric model_________________________________________

Aristarchus:______Heliocentric model__________________________________________

“The sun rises in the East and sets in the West.” What is really happening? Given an answer that explains what is really moving and in what direction it moves.__________________

____Earth rotates________________________________________________________________________________________________________________________

4. What did Eratosthenes measure and how did he do it?:___He determined the angle of the sun on the same day at noon in two different places and used trigonometry to determine the circumference of the Earth____________________

5. Who developed the first Heliocentric model and why was it not accepted?_Aristarchus; no observable parallax_______________________________________________

6. Who developed the model of the solar system that was used for 1500 years?_____________

_________Ptolemy______________________________________________

7. What type of model was it – heliocentric or geocentric?___geocentric____________

8. What problem visible in the motion of the planets were epicycles designed to solve?

___Apparent backward motion of outer planets__________________________________

9. What model of the solar system did Copernicus support?___Heliocentric___________

10. Whose model was more accurate – Ptolemy’s or Copernicus’s?__Ptolemy__________

11. What weakness in Copernicus’s model kept it from being an improvement to Ptolemy’s model?__Circular orbits_______________________________________________


12. What did Tycho Brahe fail to detect that caused him to continue to support a geocentric model?_____Parallax________________________________________________

13. What fundamental change to the preceding models did Kepler make which allowed his models to be successful?___Elliptical orbits_________________________________________________

14. What are Kepler’s three laws?

Law 1:__Ellipses_____________________________________________________________

Law 2:__Planets sweep out equal areas in equal times_________________________

Law 3:____p^2 = a^3___________________________________________________________

15. What tool did Galileo use that made his work so productive?__Telescope__________

16. What did Galileo see that showed that “heavenly bodies” were not perfect spheres?

_________Sunspots, craters, lunar mountains_____________________________

___________________________________________________________________

17. What did Galileo see that suggested that the stars were further away than previously thought?

___Milky Way, lots of stars not visible before___________________________________


II. Observations

18. What is a constellation?_____Collection of stars that are viewed as a group___________

19. Are all of the stars in a constellation close to each other?__Not necessarily_________

20. What is the ecliptic?___Plane in which lies the planets, the majority of the stars in the galaxy_

21. What is the Zenith?______Straight Up_________________________

22. About how many stars can you see standing at midnight on a dark cloudless night?_~5,000____

23. What is a circumpolar star?__Goes in a circle around the pole_________________

24. What is odd about the motions of Mars, Jupiter, and Saturn?__Appear to go backwards ____

25. Why does this odd thing occur?_Earth passes them as they move in their orbits_____________

26. What are epicycles?__Apparent backwards motion___________________________

27. What did the Greeks NOT see in the night sky that allowed them to continue to hold on to a geocentric model of the solar system?__Parallax______________________________________

28. On a clear night in an open, moonless desert far from any light source, give two reasons a constellation might not be visible to you

_Wrong hemisphere, wrong season________________________________

29. What is the (presumed) most important reason for early societies to keep close track of the celestial (astronomical) calendar?__Agriculture, when to plant___________________


III. Physics

30. What are the three hallmarks of modern science?

______Predict___________________________________________________________________

______Testable Hypotheses_______________________________________________________

______Reformulated hypotheses based on experiment_________________________

31. What is the speed of light? (Give a numerical answer) __3E8 m/s, 186282 miles / sec_________

32. Speed of the Earth’s rotation at the equator:__1000 mph______________________

33. Speed of the Earth’s rotation at Wappinger’s Falls:__700 mph_________________

34. Speed of the Earth around the sun:_70,000 mph_____________________

35. Mars has an average orbital radius of 230,000,000km and an orbital period of 690 days. How fast is it moving in its orbit?

_____2 * PI * 230,000,000 / 690 = 2,000,000 km/day____________________________

36. (T/F) A light year is the distance light travels in 12 months. True

37. What causes the acceleration due to gravity?___mass_______________________________

38. How does the mass of an object affect its rate of fall?__No difference__Why?__All mass falls at same rate________________________________________

39. How does mass differ from weight?_Mass is due to matter, Weight due to gravity_______

40. What is inertia?__Resistance of an object to acceleration________________________

41. What are Newton’s three laws of motion?

__Inertia_____________________________________________________________________

__F = ma_____________________________________________________________________

__Every action has an equal and opposite reaction_________________________

42. What is meant by an inverse square law?__An effect whose intensity decreases with the square of the distance from the source___________________________________________

43. What things are affected by inverse square laws?_gravity, light, sound, radiation______


44. Forms of energy:

Kinetic energy:___Energy of motion_______________________________________

Potential Energy:__Stored energy (gravity, spring)____________________________

Radiative Energy:__Light_______________________________________________________

Thermal Energy:___Heat_______________________________________________________

Mass Energy:______E = mc^2______________________________________________________

45. Orbital Descriptions

Ellipse:___Egg-shaped________________________________________________________

Parabola:__Open passage, will not stay in orbit___________________________________

46. What is the escape velocity of an object? Going fast enough so it will never return___

47. Why are there tides?__Gravity due to the moon___________________________

48. What is the formula for the force of gravity?__Fg = G m1 m2 / r^2__________

49. If I double the mass of an object, what happens to the force of gravity it exerts?__Doubles____

50. If I double the mass of an object, what happens to the force of gravity acting on it?_Doubles__

51. If I double the distance between two objects increases, what happens to the force of gravity between them?___Divide by 4____________________________________________________

52. If I halve the distance between two objects increases, what happens to the force of gravity between them?___Multiply by 4_________________________________________


53. What are the colors of the spectrum of visible light? (Hint: ROYGBIV)Red, Orange Yellow Green Blue Indigo Violet

54. What other types of electromagnetic radiation is like light but just not visible to us?

1._gamma________________________2._______X-rays___________________3.____________UV______________4._______________IR_________________5._________________Radio________________

55. What are the three types of spectra?

1.__Incandescent______________________________2._____________Line Emission__________________3.________________________Line Absorption_______


56. What type of body emits a continuous spectrum?

_____HOT_______________________________________________________________

57. What type of body emits an emission spectrum?__glowing gas______________________

__________________________________________________________________________

58. What type of body is associated with an absorption spectrum?_backlit cloud_____

59. What two things about the blackbody radiation of an object are affected by its temperature?

___Color, Intensity_________________________________________________________

60. What is blue shifted light?__Light shifted toward the blue end of the spectrum__________

61. When is blue shifted light observed? Something coming toward us_______________

62. What is red shifted light?_ shifted toward the red end of the spectrum _____________

63. When is red shifted light observed?_Light moving away from us__________________

What can we learn from the following diagram?


IV. The Earth

64. What causes the seasons?___Axial tilt of the Earth___________________________

65. When is the Earth closest to the Sun?__Winter______________________________

66. Which is more important to the seasons – the distance from the sun, or some other cause?

_______________Axial Tilt__________________________________________________________ 67. The slow change in the direction of the North pole is called _precession__________ and has a

cycle of about 26,000 years.

68. The axial tilt of the Earth is about _23.5____ degrees.

69. List the phases of the moon in order starting with the new moon:

New _______

_Waxing Crescent________________

_First quarter________________

_Waxing Gibbous________________

_Full________________

_Waning Gibbous________________

_Third quarter________________

_Waning crescent________________

_New________________

70. Why do we see only one side of the moon?_The moon’s rotation matches its orbital revolution

71. During what part of the lunar cycle can lunar eclipses occur?_Full_________________________

72. During what part of the lunar cycle can solar eclipses occur?_New_________________________


V. Telescopes and Optics

Aperture_____E____ A. The bending of light as it goes through a medium

Refraction_A_______ B. The measure of the ability to distinguish between two different objects that are close together

Diffraction_____G_____ C. Different colors of light come to a focus at different points.

Magnification____F_____ D. Light bouncing off a surface

Reflection________D________ E. The size of the opening of the telescope where light enters

Angular resolution__B________ F. An increase in the apparent size of an object

Chromatic aberration_C_______ G. Light bending around an edge

73. The real image formed by a convex lens is

o Right-side up c. Distorted due to atmospheric aberration o Upside-down d. Reflective

The two types of optical telescope are refracting and reflecting.

74. Which type of telescope is generally preferred by astronomers today?o Reflectingo Refracting

75. What are the major differences between reflecting and refracting telescopes?Reflecting is cheaper, greater aperture, shorter. Refracting is heavier, longer, more expensive

Refracting has more chromatic aberration

76. To reduce the effects of atmospheric turbulence, a telescope should be placed where it is o High and dryo Cold and darko Damp and foggyo Hot and dry


77. Adaptive optics involveo Changing the size of the apertureo Increasing the size of the lenso Using fans to stir the air aroundo Changing the shape of the mirror

78. What are the major problems with refracting telescopes?o Heavy, expensive, long, chromatic aberration__________________________o _______________________________________________________________

79. To increase the amount of light a telescope can gather, it needs to be madeo Longero Larger in diametero Higher in altitudeo With an eyepiece of shorter focal length

80. What is angular resolution? Ability to separate the images of two objects that are close

together

81. To decrease the angular resolution of a telescope (smaller is better), one should

o Increase the diameter and decrease the wavelengtho Increase the diameter and increase the wavelengtho Decrease the diameter and decrease the wavelengtho Decrease the diameter and increase the wavelength

82. In the table below indicate which measurements could reasonably be taken from a ground-based

telescope.

Indicate Ground (G) where appropriate

Radio G

Infrared

Visible Light G

Ultraviolet

X-ray

Gamma-ray

83. Stars twinkleo Due to imperfections in a refracting telescopeo Due to the presence of an atmosphereo Due to the Earth’s gravitational field

Mr. Davis Astronomy: 2018 Final Review o Due to variations in the brightness of a star

84. Two telescopes are linked together to simulate a telescope with a bigger aperture. For this we use the technique called

o Angular separationo Chromatic aberrationo Refractiono Interferometry

85. What are the three types of observations made using telescopes?

o _Images_____________________________________

o _Spectrum_____________________________________

o _Brightness_____________________________________


86. Label the diagrams for the two telescopes below:

a. Type of telescope: Reflecting

b. Type of telescope: Refracting


VI. The Planets

87. The plane of the __ecliptic________________ is close to the orbits of most planets.

88. Group the nine planets (including Pluto) into two groups: Big and small. Group them in irder from largest to smallest. Label them T for terrestrial and J for Jovian.

What terrestrial “world” is not on this list?

BIG small

___Jupiter_____________________ ____Mercury_____________________

Saturn_________________________ Venus_________________________

Uranus_________________________ Earth_________________________

Neptune_________________________ Mars_________________________

_________________________ Pluto_________________________

_________________________ _(Luna)________________________

89. List the nine planets in order from the sun

__Merc____________________________________

______Vensu________________________________

___________Earth___________________________

_______________Mars_______________________

__________________Jupiter___________________

________________________Saturn_____________

_____________________________Uranus________

___________________________________Neptune__

Pluto_____________________________________

Mr. Davis Astronomy: 2018 Final Review 90. Which is the archetypal Jovian planet, and which is the archetypal terrestrial planet?

o _Jupiter__________________________________________o _______Earth____________________________________

91. How does the distance between terrestrial planets compare to the distances between the Jovian planets?__Terrestrial – close together; Jovian – far apart____________________

92. The Sun: o Composition: _H/HE___________________________________________________

93. Mercury:

o What makes it unique: Close to sun

94. Venus:

o What makes it unique: Thick atmosphere, very hot

95. Earth:

o What makes it unique: Life. Lots of liquid water

96. Mars:

o What makes it unique: May once have had water

97. Jupiter:

o Composition: H/He

o What makes it unique: BIG

98. Saturn:

o Average Density: Less than Water

o What makes it unique: Rings!

o What are Saturn’s rings made of?____Ice_______________________________________

99. Uranus:

o Composition: H/He/H compounds

o What makes it unique: Rotates sideways

100. Neptune:

Mr. Davis Astronomy: 2018 Final Review o What makes it unique: Boring in appearance

101. Pluto:

o Composition: Rock and ice

o What makes it unique: Shares orbit with Neptune

102. What features of our solar system provide clues to how it was formed?

o All revolve in same way

o Most rotate the same way

o Terrestrial close to sun

o All in same plane

103. Complete the table below that compares terrestrial planets to Jovian planets.

Terrestrial Jovian

Relative Size Small Big

Relative Density High Low

Composition Rock Gas

Physical nature of surface Solid ???

Moons and Rings Few / None Lots

Relative distance from Sun Close Far

Relative surface temperature High Cold

104. What is meant by differentiation?____Separating out into different densities________

___________________________________________________________________________

105. What are asteroids and where are they found? Rocky planetesimals mostly between Mars and

Jupiter

106. What are comets and where are they found? Chunks of ice and rock, mostly past Pluto

Mr. Davis Astronomy: 2018 Final Review 107. What are the exceptions to the planetary rules? Venus (backwards), Uranus (sideways)

108. What are lunar “seas” (maria)?_____Lava flows_______________________________________

109. Why do we think there was once liquid water on Mars?_river beds, deltas_________________

110. Why is it hard to observe the features of the surface of Venus?___Thick clouds____

__________________________________________________________________________

111. What is evidence of plate tectonic motion on earth?

___Earthquakes, fault lines____________________________________________________

112. How do seismic waves help us understand what the Earth is composed of?Determine velocity of sound through different layers of the Earth, how they bend__________

113. Which planets have moons?___Most, not Mercury or Venus______________________

114. What are the rotation rates of each world? (VS, S, ~Earth, F)

Mercury______VS_______________

Venus_________VS____________

Earth:_________E______________

Mars:________E_______________

Luna:________S_______________

Jupiter:_______F_______________

Saturm:_____F_________________

Uranus:_____F_________________

Neptune:_____F_________________

Pluto:_______F_______________

115. What is the effect of the fast (~10 hour) rotation of Jupiter and Saturn on the shape of the planets?______Oblate Spheroid_________________________________________

116. (Probably) Why do Jupiter, Saturn, and Neptune emit twice as much heat as they receive from the sun?______Continued gravitational contraction________________________

Mr. Davis Astronomy: 2018 Final Review 117. Which planet has a mostly nitrogen / oxygen atmosphere?_____Earth___________________

118. Which planet has thick atmosphere that is mostly carbon dioxide (CO2)?__Venus___________

119. Which planet has a thin but noticeable CO2 atmosphere?____Mars_____________________

120. Which planets have Hydrogen, Helium, or Hydrogen compounds as the major portion of their atmospheres?_____Jup, Sat, Ur, Nep_______________________________________________

121. How does the greenhouse effect work?__Heat is trapped in atmosphere__________

122. What are the major greenhouse gases?_____CO2___________________________

________Methane________________________

_______________H2O_________________

123. What is the primary source of terrestrial atmospheric gases?___Volcano___________________

124. What is the primary source of the Earth’s oceans?__Volcano____________________________

125. What is albedo and why does it matter?___Reflectivity, reflects away heat___________

126. What are the major moons of Jupiter?______Ganymede_______________________________________

_Europa____________________________________________

Callisto_____________________________________________

______Io_______________________________________

Which is the biggest?________Gany__________________

Which is the most volcanically active?______Io_________________

What is the source of the internal heat for Jupiter’s moons?__Tidal interactions with Jupiter_

127. What is the major moon of Saturn?_______Titan___________________________________

128. What is significant about Saturn’s largest moon?__Atmosphere, liquid methane_____________

129. Which other of Saturn’s moons might be a place where life could exist? It is geologically active in spite of its small size. __Enceladus_________________________________________

130. What is the likely source for Jupiter’s ring?____Io’s volcanos_____________________

131. What is significant about Europa? Describe its likely construction


___Ice covering liquid ocean________________________________________________

VII. Nebular Hypothesis

132. What is a nebula?____Cloud of gas________________________________________

133. What are the general outlines of the nebular hypotheses for solar system formation?__________

__Cloud of gas collapsed due to gravitation, formed planets and star______________________

134. What is the hypothesis of galactic recycling?_Stars explode spewing gases and metals which are absorbed into later stars_

_______________________________________________________________________________

135. What is the difference between a “first generation” star and “second generation” or later stars?

_First generation starts with H only, later have more elements____________________________

136. What does angular momentum mean, and how does it apply to our understanding of the formation of the solar system?

___The tendency of a rotating object to keep rotating__________________________________

137. As a solar nebula collapses,

a. What happens to its temperature?______Up________________________________________

b. What happens to the spin of the nebular?_____Faster_____________________________

c. What happens to the general shape?____Pancake________________________

138. What evidence to we have from telescopic observation that supports the nebular hypothesis?

_____Have seen nebulae forming solar systems_____________________

139. What is the proposed composition of the solar nebula?_Mostly H and He___________

140. What event is believed to have transformed the solar nebula?___Ignition of Sun_____

141. Is the sun’s output (luminosity) constant?__No, slowly increases_______________

142. What is the frost line?_Water, H, He mostly driven out past the frost line_/ Solar heat________

143. What stayed within the frost line and what was forced outside it?____Rock stayed inside_________

144. What are planetesimals?____Chunks of rock and Ice that collected as nebula collapsed

Mr. Davis Astronomy: 2018 Final Review 145. What would happen to planetesimals over time?___Aggregate under influence of gravity_____

146. What is the solar wind?__Nuclei and electrons streaming out from the sun___________

147. What does the period of “heavy bombardment” mean and why would it have occurred?________

__Planetesimals coalescing and colliding into a larger body until most of them were absorbed_______

148. Over time, a large enough object will become __round________________ in shape. 149. What causes planets to be hot inside?

Initially, ____leftover heat___________________ __________________ ____________ from the initial aggregation of the material into a single body.

Additional energy comes from the _kinetic energy_____________ ____________ of meteors as they strike the planet.

Most energy currently comes from __radioactive decay____________________ __________.

The interior of the planet cools by _convection__________________ of material from the core to the upper mantle, then _cunduction ___________________ of heat through the crust, and finally __radiation_________________ of energy into space.

150. Given two planets of the same composition, which cools faster – a large one or a small one?___Small________________

151. Which terrestrial worlds are now probably geologically dead?_Mercury, Luna______________

152. Which terrestrial worlds are probably still geologically active?_Earth, Venus_________________

153. Which terrestrial planet has the largest magnetic field?__Earth_____________________

154. What 3 things appear necessary for a strong magnetic field in a terrestrial planet? Moderate rotation, conductive material inside, energy source

155. What 4 things change the surface of a planet?

_Erosion_______________________________ __Vulcanism________________

_Meteors_______________________________ __Tectonics____________

156. There are more _Small_________ craters than __big____ craters.

Mr. Davis Astronomy: 2018 Final Review 157. Small planets tend to have ___less atmosphere___________ _____________________ and

therefore less surface erosion.

158. The slower the _rotation______________ rate the less weather!

159. How do seismic waves help us understand what the Earth is composed of?______S and P waves travel differently through different materials._____________

160. What is the solar wind and what affect might it have on planetary atmospheres?______

___Solar wind impacting atmosphere might slowly strip it off into space____________

161. What shields Earth from the solar wind?___magnetic field_________________

162. What other planets have similar shielding?__Joviam planets__________________

163. What planet’s atmosphere argues against this shielding being important in maintaining an atmosphere?____Venus_________________________________________________

164. What is a comet made of?___Ice, dust, rocks______________________________

165. Which way does the comet’s tail point?___Away from the sun_________________

166. Comets appear to come from two general locations.

Which one is closer?__Kuiper belt_______________________________________________

Which one is in the plane of the ecliptic?__Kuiper belt_______________________________

Which one is farther away?___Oort cloud_________________________________________

Which one is a spherical halo of cometary material?_Oort cloud_______________________

167. Why do we believe the asteroids did not condense into a planet?_Jupiter’s gravity____

168. What is the life cycle of a comet?_Cold, warm (loses material), cold, warm, cold, eventually runs out of stuff and meteor shower is left___________

169. What are the characteristics of a planet and which does Pluto lack?

_Spherical, cleared orbit of other stuff, orbits star__________________________________________

_Pluto has not cleared orbit__________________________________________

170. How can we detect extrasolar planets?


1 ) _Doppler effect_ __ __ __ __ __ __ __ __ __ __ __ __ 2) __Transit __ __ __ __ __ __

3) Direct observation__ __ __ __ __ __ __ __ __ __ __ __ __

171. What types of extrasolar planets have been discovered?

__Terrestrial_____________________________________________

__Hot Jupiters_____________________________________________

172. How do the orbits of most planets discovered thus far compare to the orbits in our solar system?___Highly eccentric_________________________________________


VIII. Review – The Sun

173. Label the layers of the Sun in the figure below. Fill in each box with the appropriate label

and approximate temperature.

174. The layer of the Sun we see is called the Photosphere .

175. The Sun produces its energy through fusion by converting four atoms of

Hydrogen into one atom of Helium

Chromosphere 10,000-100,000K

Radiation zone 10,000,000K

Corona 1,000,000K

Convection Zone

Photosphere 6,000K

Core 15,000,000K


. In order for this process to occur, there must be very high pressure

and temperature in the core.

.

176. Nuclear power plants produce energy through a process called fission .

177. Scientists expect our Sun to last for another 5,000,000,000 years.

178. Define solar flare. An ejection of material (plasma) from the surface of the sun after a

recombination of magnetic field lines

179. Define solar prominence. Solar plasma rising from the surface of the sun and returning

to the surface following magnetic field lines.

180. What’s a sunspot? A cooler region on the sun’s surface (where magnetic field lines leave

the surface)

181. Solar prominences are often associated with sunspots.

182. The sunspot cycle lasts about 11 years.

183. Solar flares have been known to disrupt

electrical power distribution and damage satellites.

184. What two processes, working together, keep the sun in balance?

Process 1:_______Gravity___________________________________________________________

Process 2:_______Fusion___________________________________________________________

185. Where does fusion occur?__Core____________________________

186. Through what layer do gamma ray photons travel by diffusion?_radiation zone_____________

187. Through what layer does energy convect toward the surface?__convection zone_____________

188. What is the layer that produces most of the ultraviolet radiation?_Chromosphere___________

189. What is the layer we see in an eclipse?____Corona__________________________

190. What is the outer layer of the sun’s atmosphere which extends far out into space?________

____Solar wind_____________________________________________________________________


191. What is stellar luminosity?_The inherent brightness of a star______________________

192. What is the difference between apparent luminosity and actual luminosity?__Apparent luminosity is how bright it looks from here. Actual luminosity si how bright it looks from

a standard distance._________________________

193. What do the colors of stars tell us about their temperature?__More blue = hotter, red = cooler – black body radiation_

194. List the spectral types from hottest to coldest:__OBAFGKM_____________________________

195. How do we measure stellar masses?__Period of a binary system___________________

196. What is a Hertzsprung-Russell diagram?__A diagram showing stellar temperatures and luminosities_________

197. What is the Main Sequence?____hydrogen burning stars___________________________

198. What are giants and supergiants?__Helium burning stars that have left the main sequence____

199. What is the difference between main sequence stars and Giants / Supergiants in terms of the fuel consumed?___Hydrogen vs. Helium_________________________________

200. What are white dwarfs?_Stars that have burned up fule, shrunk down, and are now just cooling_____

201. Which stars have the shortest lifetimes?_Large blue_________________________

202. Which stars have the longest lifetimes?__Red dwarf___________________________

203. What is the relationship between luminosity and lifetime?_more luminous – shorter life_____

204. What is a Cepheid variable? A variable star running on a branch of the main sequence_______


IX. The End

205. When a large cloud of gas in a galaxy ejected from a supernova runs into a large cloud of gas ejected from another supernova, what may occur?

______Star formation________________________________________________

206. Why do astronomers look at light at different frequencies (wavelengths)?_____Different features visible at different wavelengths___________________________

207. What is probably at the center of most galaxies?__Black Hole_______________

208. What do astronomers measure that causes them to think that the universe is accelerating?___red shift____________________________________________

209. What is Hubble’s Law?_Further away – moving faster away___________________

210. What would be needed to keep the universe from accelerating?__More mass_

211. What does the acceleration of the universe tell us about its origin?_It started out as a compact object_______

212. What is “dark matter”?__Material producing gravity we cannot otherwise see or detect._

213. What is “dark energy”?__Something causing the universe to accelerate its expansion_____

214. What proportion of the universe appears to be made of “normal” matter?__5%___________

215. What is a WIMP?__Proposed dark matter particle (Weakly interacting massive particle)_____

216. What do we mean when we say that the universe is expanding?o Average distances are increasing between galaxies?o The statement is not meant to be literal; rather, it means that our knowledge of the

universe is growing?

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