Sky

#небо #sky

A post shared by Vasiliy S. Znamenskiy (@znamenski) on Sep 1, 2017 at 3:29pm PDT

Sunset

#закат #sunfall

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Beautiful Vocal Chillout Compilation Vol. 4

Eclipse 2017: Through the Eyes of NASA

Vasiliy Znamenskiy

General Astronomy

Марс Тайна красной планеты HD

Midterm Exam - BMCC - AST 110 - 4/5/2017

1. The symbol “F” in the formula F = GM₁M₂/r² means the _____________.
   a) focal length, b) fusion, c) frequency, d) Fahrenheit temperature, e) force,
   
2. Angles: 1° + 60' + 3600'' = ______°;
   a) 3661, b) 1603600, c) 180, d) 10800, e) 3.
   
3. Right ascensions: 120^s + 58^m + 2^h = _________;
   a) 180, b) 180°, c) 3, d) 3^h, e) 3°
   
4. How many times atmospheric pressure on Venus is greater than on the Earth?
   a) 2; b) 9; c) 20; d) 90; e) 200.
   
5. Which terrestrial planete has greatest surface gravity?
   a) Mercury; b) Venus; c) Earth; d) Mars; e) Moon.
6. Which terrestrial planete has longest solar day?
   a) Mercury; b) Venus; c) Earth; d) Mars; e) Moon.
7. How meny Mercury's solar days are in one Mercury's solar year?
   a) 0.5; b) 5; c) 50; d) 500; e) 365.
8. Which terrestrial planete has the largest volkano known in the solar system?
   a) Mercury; b) Venus; c) Earth; d) Mars; e) Moon.
9. Wich planet of the solar system is largest?
   a) Venus; b) Earth; c) Mars; d) Jupiter; e) Saturn.
10. Wich planet of the solar system has lowest average density?
    a) Venus; b) Earth; c) Mars; d) Jupiter; e) Saturn.
11. Wich planet of the solar system has shortest solar day?
    a) Venus; b) Earth; c) Mars; d) Jupiter; e) Saturn.
12. Wich part of the Sun emits the radiation we see?
    a) Solar Wind; b) Corona; c) Transition zone; d) Chromosphere; e) Photosphere;
13. 1 light-year / 1 AU = ? a) 1; b) 63240; c) 1000; d) 6.32x10²⁰; e) 1.58 × 10^-5.
14. M☉ / M = ? a) 3'330.6; b) 33'306; c) 333'060; d) 3'330'600; e) 33'306'000.
15. R☉ / R = ? a) 0.109; b) 1.09; c) 10.9; d) 109; e) 1090.
16. Light travels from the Sun to Earth in about
    a) 0.8 s; b) 8 s; c) 80 s; d) 8 minutes; e) 80 minutes.
17. The mean distance of the Sun from the Earth is approximately ______ astronomical units.
    a) 0.1; b) 1; c) 10; d) 100; e) 1000.
18. Which statement best describes Earth’s approximate rates of rotation and revolution?
    a) Earth’s rotation rate is 15°/hour and its revolution rate is 1°/day; c) Earth’s rotation rate is 1°/hour and its revolution rate is 15°/day; d) Earth’s rotation rate is 24°/hour and its revolution rate is 360°/day. e) Earth’s rotation rate is 36.
19. Which layer of the sun has the highest temperature?
    a) core; b) photosphere; c) chromosphere; d) corona; e) spiral.
20. Why do the planets in our solar system stay in their positions?
    a) The sun's radiation keeps them there; b) They travel the same distance from each other; c) The sun's gravity keeps them in place; d) Friction with the atmosphere keeps them from escaping; e) E = mc².
21. During which phase of the Moon do we see the entire lighted side of the moon? a) new Moon; b) first quarter; c) full Moon; d) waning gibbous; e) electric blue.
22. Which term do we use when we are seeing more and more of the lighted portion of the Moon each night? a) full; b) waning; c) waxing; d) new; e) spiral.
23. How long does it take the Moon to rotate on its axis? a) about 25.3 days; b) about 27.3 days; c) about 30 days; d) about 2 months; e) about 1 year.
24. When do spring tides occur? a) during a new Moon; b) during a first quarter Moon; c) during a waxing gibbous Moon; d) during a waning crescent Moon; e) during a spiral Moon.
25. What is it called when the Moon is closest to Earth in its orbit?
    a) spring; b) neap; c) apogee; d) perigee; e) spiral.
26. The tilt of Earth's rotation axis relative to ecliptic is responsible for the _________ we experience.
    a) seasons, b) years, c) days, d) rotational speed, e) rotational frequency
    
27. As the Sun crosses from the northern into the southern celestial hemisphere, we have the ___________.
    a) tropical year, b) vernal equinox, c) sidereal year, d) precession, e) autumnal equinox.
    
28. Starting from the ___________, which is all but invisible in the sky, the Moon appears to wax.
    a) full Moon, b) gibbous Moon, c) quarter Moon, d) new Moon, e) blue Moon.
    
29. The ___ Moon rises in the east as the Sun sets in the west.
    a) full, b) gibbous, c) third quarter, d) new, e) first quarter.
    
30. The Sun's light is not blocked by Earth at the full phase because the Moon's orbit is ______.
    a) circular, b) elliptical, c) inclined, d) incommoded, e) curved.
    
31. __________model of the universe has the Sun, Moon, and planets all orbiting Earth.
    a) Ptolemaic, b) Heliocentric, c) Copernican, d) Retrograde, e) Gravitational.
    
32. Planetary orbits are ellipses having the Sun as one _________.
    a) center, b) axis, c) gravity, d) focus, e) fireplace.
    
33. The average distance from Earth to the Sun is one astronomical ____.
    a) distance, b) unit, c) kilometer, d) light year, e) parsec.
    
34. To change a body's velocity, a ______ must be applied.
    a) acceleration, b) force, c) charge, d) mass, e) speed.
    
35. Every object having any ______ exerts a gravitational force on all other objects having the same.
    a) speed, b) acceleration, c) position, d) mass, e) direction.
    
36. The number of wave crests passing any given resting point per unit time is called the wave's _____ .
    a) period, b) wavelength, c) amplitude, d) speed, e) frequency.
    
37. Wavelength of peek emission ? 1/ ______________ .
    a) temperature in K°, b) temperature in F°, c) temperature in K, d) frequency, e) period.
    
38. The long axis of the ellipse is known as the ___________ .
    a) semimajor axis, b) perihelion, c) aphelion, d) eccentricity, e) major axis.
    
39. The _________ of the ellipse is equal to the distance between the foci divided by the length of the major axis.
    a) semimajor axis, b) perihelion, c) aphelion, d) eccentricity, e) major axis.
    
40. An imaginary line connected the Sun to any planet sweeps out equal ____ of the ellipse in equal intervals of time.
    a) lengths, b) areas, c) volumes, d) angles, e) pieces.
    
41. The planet's _________ is its point of closest approach to the Sun.
    a) perihelion, b) aphelion, c) eccentricity, d) equinox, e) summer solstice.
    
42. The square of a planet's orbital period is proportional to the _____ of its semimajor axis.
    a) length, b) size, c) cube, d) sphere, e) square.
    
43. The orbital semimajor axis of the _______ is equal about 5 AU.
    a) Mercury, b) Venus, c) Earth, d) Mars, e) Jupiter.
    
44. If P is the Saturn's sidereal orbital period in Earth years and a is its semimajor axis in astronomical units then calculation of the ratio ______ gives the numerical result about 1.
    a)P/a b) P³/a² c) P³/a d) P²/a³ e) P/a³
    
45. If the distance between to object is increased 3 times then the gravity attraction of this bodies to each other is ___________ .
    a) decreased 9 times, b) decreased 3 times, c) increased 3 times , d) increased 9 times,
    e) decreased 2 times.
    
46. Which terrestrial planete has hotest surface temperature?
    a) Mercury; b) Venus; c) Earth; d) Mars; e) Moon.
47. Which terrestrial planete is in retrograde rotation?
    a) Mercury; b) Venus; c) Earth; d) Mars; e) Moon.
48. The Sun’s energy output is fueled by the fusion of __________ into helium.
    a) nucleus; b) mercury; c) hydrogen; d) calcium; e) oxygen
    
49. Which of the following have an icy composition?
    a) stars; b) planets; c) comets; d) asteroids; e) moons.
50. Which layer of the sun is only seen during a total solar eclipse?
    a) core; b) photosphere; c) corona; d) convective zone; e) time zone.

Astronomy Music

Astronomy Music #Astronomy #Music #AstronomyMusic pic.twitter.com/q1quGzRxSk

— General Astronomy (@GenAstronomy) April 5, 2017

Chapter 9: The Sun. Our Parent Star. Quiz # 7

Student Last Name________________First Name_______________Date/__/____17

1. The Sun is about ____ light-minutes from Earth.

2. Light from the Sun won’t have reached Pluto for another __ hours

3. Light from the Sun won’t have reached the nearest star for over __ years.

4. The Sun’s mass is about ____________ times the mass of Earth.

5. The “surface” of the Sun is the ___________, which is the layer we see.

6. The _______ is the area of the Sun where temperatures are high enough for the energy production to occur.

7. In the _____________ zone, the temperatures are lower, but still high enough that all the atoms are ionized and the radiation travels freely.

8. In the ______________ zone, the temperatures are even lower, and electrons are now bound to nuclei; atoms absorb the photons so the energy can no longer be transported through radiation.

9. The _______________ is the visible surface of the Sun.

10. The ______________ is only visible during a solar eclipse, as it is dimmer than the ______________.

11. The ____________ is the wide layer that extends out into space, eventually turning into the solar wind. It is also only visible during a total solar eclipse. One reason astronomers get so excited about solar eclipses is that they provide a rare opportunity to view and study these layers of the Sun.

12. The radius of the core is __________ km

13. The radiation zone is ___________ km thick

14. The convection zone is ______________km thick

15. The photosphere is ______________km thick

16. The chromosphere is ______________km thick

17. The transition zone is ______________km thick

18. Energy is produced in the ________.

19. The solar surface of the Sun is ______ K.

20. The interior of the Sun is about ______ K.

21. Knowing basic facts about the Sun, such as its mass, composition, and physical processes, allows astronomers to predict the entire structure of the Sun. This is known as a _______.

22. The most obvious evidence of solar ______________ is solar granulation. The granules are the tops of the ___________ cells as they rise and fall. The motions of the cells can be measured directly.

23. Because the corona of the Sun is extremely ________, some of the gas can escape into space; it escapes the gravity of the Sun.

24. The rush of particles away from the Sun is known as the solar __________.

25. ___________ are caused by kinks or loops of magnetic field extending through the lower atmosphere.

26. P__________ are caused by very large loops of magnetic field that carry luminous gas far above the solar surface.

27. The number of __________ varies considerably over an 11-year cycle. At the peak of the cycle there may be hundreds of ___________; at the minimum there may be virtually none

28. The Sun’s energy output is fueled by the fusion of __________ into helium.  

Meteoroid - Meteor - Meteorite

From a meteoroid to a meteor and meteorite: how a meteoroid enters the atmosphere to become visible as a meteor and impact the Earth's surface as a meteorite.

The asteroids of the inner Solar System and Jupiter.

Hubble Detects a Rogue Supermassive Black Hole

National Geographic | Gravity - Documentary HD 1080p

A Traveller's Guide to the Planets: Venus and Mercury - Full length docu...

Lucky Seven Star

by Chris Larson | March 2017
The discovery of planets orbiting stars other than the Sun was news 20 years ago, but is not any longer. Even the discovery of Earth-like planets is no longer remarkable, since a fair number have been recorded in recent years. But the discovery of a relatively close star orbited by seven planets, all to some degree Earth-like, and all orbiting at a distance from the star that might allow for the presence of liquid water—that is unprecedented, and certainly newsworthy. This discovery was announced in a study appearing in Nature in February 2017.

NASA/JPL-Caltech

The discovery of Earth-like planets is no longer remarkable, since a fair number have been recorded in recent years. But the latest discovery of a relatively close star orbited by seven planets, all to some degree Earth-like, and all orbiting at a distance from the star that might allow for the presence of liquid water—that is unprecedented.

The title of the Nature paper gets right to the point of what the astronomers found: "Seven Temperate Terrestrial Planets around the nearby Ultracool Dwarf Star TRAPPIST-1." Michael Gillon was the lead author of the study, which was conducted by a team with members from a number of countries, including the U.S., Belgium, France and Britain.

Ultra-Cool

TRAPPIST-1 is located about 12 parsecs, or 39 light-years, away from the Sun. It is a great deal smaller, cooler and dimmer than the Sun. It is also much less massive—it has about 8% of the Sun's mass. It is about the size of Jupiter, although it is denser: it has roughly 80 times the mass of Jupiter. The low core temperature means that it is barely able to fuse hydrogen into helium, and does so at a low rate. The low fusion rate translates into a long lifetime, much longer than that of the Sun and of stars of roughly the same size as the Sun or larger.

NASA/JPL-Caltech/M. Bank

TRAPPIST-1 is located about 12 parsecs, or 39 light-years, away from the Sun. It is a great deal smaller, cooler and dimmer than the Sun. It is also much less massive—it has about 8% of the Sun's mass. It is about the size of Jupiter, although it is denser.

TRAPPIST is an acronym for the TRAnsiting Planet and Planetesimals Small Telescope. The telescope that discovered the planets circling TRAPPIST-1 is about 60 centimeters (24 inches) in diameter and is located in Chile. After the initial find by TRAPPIST, further observations were made by a number of other telescopes, including the Spitzer Space Telescope.

Top: ESO; Center and Bottom: NASA/JPL-Caltech

TRAPPIST, the telescope that discovered the planets circling TRAPPIST-1, is about 60 centimeters (24 inches) in diameter and is located in Chile. The initial survey by TRAPPIST, and a subsequent closer look by other telescopes, yielded enough information to deduce the existence of seven Earth-like plants that included data on orbital periods, distance to TRAPPIST-1, planet radius and planet mass.

TRAPPIST focuses on ultra-cool stars, stars with less than 15% of the mass of the Sun. There are a number of reasons for concentrating on these stars, the researchers point out:

• Ultra-cool stars are the most common stars in our galaxy, and thus learning about the planets that orbit them means presumably learning about the most common planets in our galaxy.

• These stars are small—and detection by the transit photometry method of planets orbiting small stars is much easier. This method measures the light emitted by a star; when a planet passes in front of the star (more precisely, when a planet passes between the star and the Earth—a passage referred to as a "transit"), the light output falls. On a website about TRAPPIST-1 curated by the researchers, they note that "the small size of the host star means the transit signals produced by Earth-sized planets are 80x more pronounced compared to similar planets transiting a Sun-like star (the signals from the atmosphere are also enhanced by 80 times)."

• Current technology allows researchers to determine the radius and massof an Earth-like planet with an Earth-like temperature if the planet orbits an ultra-cool dwarf star, but not when it is orbiting a star like the Sun.

• Planets orbiting ultra-cool dwarf stars share a number of characteristics with Earth, but differ in significant respects as well: they differ in the amount of radiation received, and presumably also always have the same side turned to their star. This mix of familiar and unfamiliar aspects should enlarge our understanding of how different factors combine to create climate and other phenomena.

Near Resonance

The initial survey by TRAPPIST enabled the researchers to identify three planets circling the star; the subsequent closer look by a suite of telescopes yielded enough information to deduce the existence of four more. The six inner planets, the researchers observe in their paper, "form a near-resonant chain, such that their orbital periods (1.51, 2.42, 4.04, 6.06, 9.1 and 12.35 days) are near-ratios of small integers." (An orbital period is how long it takes a planet to complete an orbit—for Earth this is 365 days, roughly, but since these planets are much closer to a much smaller star, their orbital periods are much shorter.) The ratios mean that the planets will have regularly recurring times when they are close enough to each other to have a significant gravitational interaction, and this can cause small changes in the transit times for the planet. The masses of the planets can be estimated as a result.

NASA/JPL-Caltech

TRAPPIST-1 is small, and the detection of planets by transit photometry—measuring the light emitted by a star—was continuously monitored by the Spitzer Space Telescope and ground-based data collectors from September 19, 2016 to October 10, 2016. When a planet passed between the star and the Earth, the light output fell. These observations enabled researchers to establish the relative positions of the planets' orbital phases.

The research team observed that accepted theory on how planets form suggests that the TRAPPIST-1 planets formed further from their star than they presently are, and then migrated inwards. This is what is thought to have happened with the moons of Jupiter, for example. If the TRAPPIST-1 planets formed where it is thought they did, their composition would reflect what was found in that part of the disc of materials around the star, and this in turn would mean that they probably have lower densities than Earth.

Wait Till Next Year

Investigations into the TRAPPIST-1 system are in a sense just beginning. The James Webb Space Telescope is supposed to be launched into orbit in 2018, and if it is and the telescope performs as planned, we should be able to obtain information on what sort of atmospheres the planets have and get a better idea of their temperatures. This would allow the researchers to delve into the climates of the planets.

NASA/JPL-Caltech

Investigations into the TRAPPIST-1 system are in a sense just beginning. The James Webb Space Telescope is supposed to be launched into orbit in 2018, and along with other new astronomical tools, should enable researchers to gather additional information on the atmosphere and habitability of the planets.

Is there, or was there ever, any liquid water on any of the planets? We don't know yet, but the possibility certainly can't be ruled out.

Other new astronomical tools will be coming on line in addition to the Webb telescope; in particular, a bigger and better version of TRAPPIST, called the Search for Planets EClipsing ULtra-COOl Stars (SPECULOOS), currently under construction in Chile. The new facility will be able to home in on many more ultracool stars than TRAPPIST.

NASA Jet Propulsion Lab

The reason for the excitement about the TRAPPIST-1 discovery is that it suggests that Earth-like planets are abundant in our galaxy. Increasingly, the odds seem to indicate that Earth is not alone in the universe.

The reason for the excitement about the TRAPPIST-1 discovery is that it suggests that Earth-like planets are abundant in our galaxy, the Milky Way. This can't be regarded as proven, since conceivably the discovery of seven such planets orbiting TRAPPIST-1 could be a lucky accident. But, increasingly, the odds seem to indicate that Earth is not alone; and if you are hoping to find life elsewhere in the universe, that must be regarded as good news, since to date Earth is the only place we know of where life has evolved.

Discussion Questions

Earth and the other planets in the Solar System orbit in a fairly small plane or slice of space, called the ecliptic plane. You can visualize this as a CD with, at the center, a small ball representing the Sun. Suppose someone living on a planet orbiting another star looked at the Sun—would they see the Earth transiting in front of the Sun? What would such an observation depend on?

Journal Abstracts and Articles

(Researchers' own descriptions of their work, summary or full-text, on scientific journal websites.)

Gillon, Michael, et al. "Seven Temperate Terrestrial Planets around the nearby Ultracool Dwarf Star TRAPPIST-1." Nature (Feb. 23, 2017) [accessed March 1, 2017]: http://www.nature.com/nature/journal/v542/n7642/full/nature21360.html.

Bibliography

Clery, Daniel. "Seven Potentially Habitable Earth-Sized Planets Spied around Tiny Nearby Star." Science (Feb. 22, 2017) [accessed March 2, 2017]: http://www.sciencemag.org/news/2017/02/seven-potentially-habitable-earth-sized-planets-spied-around-tiny-nearby-star.

"TRAPPIST-1" Website curated by TRAPPIST-1 researchers [accessed March 2, 2017]: http://www.trappist.one/.

Gillon, Michael, et al. "Seven Temperate Terrestrial Planets around the nearby Ultracool Dwarf Star TRAPPIST-1." Nature (Feb. 23, 2017) [accessed March 1, 2017]: http://www.nature.com/nature/journal/v542/n7642/full/nature21360.html.

Snellen, Ignas A. G. "Astronomy: Earth's Seven Sisters." Nature (Feb. 23, 2017) [accessed March 1, 2017]: http://www.nature.com/nature/journal/v542/n7642/full/542421a.html.

Keywords

TRAPPIST, TRAPPIST-1, TRAnsiting Planet and Planetesimals Small Telescope , SPECULOOS, Search for Planets EClipsing ULtra-COOl Stars, dwarf star, terrestrial planets, Michael Gillon

State of weightlessness

Earth Mass in Kilograms

If you record the Earth mass in kilograms as an integer, how many figures will be in this number?

— EarthScienceTutor (@EarthScienceTut) March 16, 2017

General Astronomy AST 110, Quiz 4

1. Frequency = 1/ __________
a) period, b) time, c) seconds, d) tension, e) speed

2. 0.2 Hz = 1/_____
a) 5, b) 5m, c) 5 Hz, d) 5 s, e) five

3. The tilt of Earth's rotation axis relative to the ecliptic is responsible for the _________ we experience.
a) seasons, b) years, c) days, d) rotational speed, e) rotational frequency

4. As the Sun crosses from the northern into the southern celestial hemisphere, we have the ___________.
a) tropical year, b) vernal equinox, c) sidereal year, d) precession, e) autumnal equinox.

5. Starting from the ___________, which is all but invisible in the sky, the Moon appears to wax.
a) full Moon, b) gibbous Moon, c) quarter Moon, d) new Moon, e) blue Moon.

6. The ___ Moon rises in the east as the Sun sets in the west.
a) full, b) gibbous, c) third quarter, d) new, e) first quarter.

7. The Sun's light is not blocked by Earth at the full phase because the Moon's orbit is ______.
a) circular, b) elliptical, c) inclined, d) incommoded, e) curved.

8. __________model of the universe has the Sun, Moon, and planets all orbiting Earth.
a) Ptolemaic, b) Heliocentric, c) Copernican, d) Retrograde, e) Gravitational.

9. Planetary orbits are ellipses having the Sun as one _________.
a) center, b) axis, c) gravity, d) focus, e) fireplace.

10. The average distance from Earth to the Sun is one astronomical ____.
a) distance, b) unit, c) kilometer, d) light year, e) parsec.

11. To change a body's velocity, a ______ must be applied.
a) acceleration, b) force, c) charge, d) mass, e) speed.

12. Every object having any ______ exerts a gravitational force on all other objects having the same.
a) speed, b) acceleration, c) position, d) mass, e) direction.

13. The number of wave crests passing any given resting point per unit time is called the wave's _____.
a) period, b) wavelength, c) amplitude, d) speed, e) frequency.

14. Wavelength of peek emission ∝ 1/ ______________ .
a) temperature in °C, b) temperature in °F, c) temperature in K, d) frequency, e) period.

15. The long axis of the ellipse is known as the ___________ .
a) semimajor axis, b) perihelion, c) aphelion, d) eccentricity, e) major axis.

16. The _________ of the ellipse is equal to the distance between the foci divided by the length of the major axis.
a) semimajor axis, b) perihelion, c) aphelion, d) eccentricity, e) major axis.

17. An imaginary line connected the Sun to any planet sweeps out equal ____ of the ellipse in equal intervals of time.
a) lengths, b) areas, c) volumes, d) angles, e) pieces.

18. The planet's _________ is its point of closest approach to the Sun.
a) perihelion, b) aphelion, c) eccentricity, d) equinox, e) summer solstice.

19. The square of a planet's orbital period is proportional to the _____ of its semimajor axis.
a) length, b) size, c) cube, d) sphere, e) square.

20. The orbital period of the Venus is equal about ________of Earth years.
a) ¼ b) 3/5 c) 1 d) 2 e) 12

21. The orbital semimajor axis of the _______ is equal about 5 AU.
a) Mercury, b) Venus, c) Earth, d) Mars, e) Jupiter.

22. If P is the Saturn's sidereal orbital period in Earth years and a is its semimajor axis in astronomical units then the calculation of the ratio ______ gives the numerical result about 1.
a) P/a b) P³/a² c) P³/a d) P²/a³ e) P/a³

23. The rate of change of the velocity of an object – speeding up, slowing down, or changing direction – is called its _________.
a) gravity, b) force, c) acceleration, d) frequency, e) speed.

24. Every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of the masses of the particles and inversely proportional to the _____ of the distance between them.
a) value, b) length, c) cube, d) unit, e) square.

25. The tendency of an object to keep moving at the same speed and in the same direction unless acted upon by a force is known as _______.
a) inventia, b) inertia, c) potentia, d) inactivity, e) speed.

26. What means the symbol P in the following formula:
(P )² = (a in astronomical units)³ / (M total in solar units) ?
a) Ptolemy, b) orbital period in Earth years, c) orbital period in Earth days, d) perimeter, e) Parallax.

27. The temperature of an object is a measure of the _____ with which its constituent particles move.
a) heat, b) speed, c) mass, d) frequency, e) spectrum.

28. Many hot objects emit a ________ spectrum of radiation, containing light of all wavelengths.
a) continuous, b) emission, c) absorption, d) continental, e) Copernican.

29. A hot ___ may produce a spectrum, consisting only of a few well-defined specific frequencies.
a) solids, b) liquids, c) gas, d) electromagnetic field, e) gamma rays.

30. The line-of-sight velocity of an object is measured my determining the Doppler shift of its ____.
a) mass, b) position, c) speed, d) size, e) spectral lines.

31. Atoms are made up of _____ charged electrons orbiting a nucleus.
a) contrary, b) well, c) negatively, d) nonconformably, e) positively.

32. The temperature of an object emitting a continuous spectrum can be measured by matching the overall distribution of radiation with a ___________ .
a) blackboard curve, b) blackbody curve, c) emission spectrum, d) radio wave, e) diffraction.

33. Only a small fraction of the radiation arriving at our planet from space actually reaches Earth's surface because of the __________ of Earth's atmosphere.
a) opacity, b) diffraction, c) interference, d) Doppler shift, e) inertia.

34. Wavelength × frequency = ________ .
a) wave period, b) mass, c) wavelength, d) amplitude, e) speed.

35. Visible light is the particular type of ______________ . a) sound waves, b) gravity, c) a beam from the eye, d) electromagnetic radiation, e) waves in luminiferous ether.
36. Total energy radiated per second ? __________ .
a) temperature, b) temperature², c) temperature³, d) temperature?, e) temperature?.

37. The symbol “∝” means “_________”.
a) infinity, b) is equal to, c) is proportional to, d) isn't equal to, e) approximately.

38. Photon energy ∝ radiation _________ .
a) frequency, b) intensity, c) power, d) wave length, e) speed.

39. A “red” photon having a frequency of _________ .
a) 4×10¹⁴, b) 4×10¹⁴ Hz, c) 4×10¹⁶, d) 4×10¹² Hz, e) 4×10¹⁴ m/s.

40. If the wavelength of an electromagnetic radiation is equal to 10 m then this radiation is called ______. a) gamma rays, b) x-rays, c) visible light, d) microwave radiation, e) radio waves.

41. If the frequency of an electromagnetic radiation is equal to 10²³ Hz then this radiation is called ______. a) gamma rays, b) x-rays, c) visible light, d) microwave radiation, e) radio waves.

42. _____ light is a mixture of colors.
a) Red, b) Yellow, c) Green, d) White, e) Black.

43. The _______ color has the largest wavelength of the visible light.
a) Red, b) Yellow, c) Green, d) Violet, e) Black.

44. The _______ color has the smallest frequency of the visible light.
a) Red, b) Yellow, c) Green, d) Violet, e) Black.

45. If the wave period of some radiation is equal to 0.1 s then the frequency of this radiation is ________ . a) 0.1 Hz, b) 1 kg, c) 10 kg, d) 100 Hz, e) 10 Hz.

46. If the speed of some waves is equal to 100 m/s and the wavelength is equal to 1 m then the frequency of this waves is ________. a) 100 Hz, b) 0.01 Hz, c) 100 s, d) 0.01 s, e) 101 Hz.

47. The symbol “r” in the formula F = GM₁M₂/r² means the _____________.
a) force, b) redshift, c) right ascension, d) frequency, e) distance.

48. The symbol “F” in the formula F = GM₁M₂/r² means the _____________.
a) force, b) redshift, c) right ascension, d) frequency, e) distance.

49. If the semimajor axis of planet “A” is 4 times greater than for planet “B” then the orbital period of planet “A” is ___ times greater than for planet “B”.
a) 1, b) 2, c) 4, d)8, e) 16.

50. If the distance between to object is increased 3 times then the gravity attraction of this bodies to each other is ___________.
a) decreased 9 times, b) decreased 3 times, c) increased 3 times, d) increased 9 times, e) decreased 2 times.