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By tradition the direction of an object in the sky needs two coordinates to describe it because the normal description does not include the distance.
The position (or direction) can be expressed as azimuth (angle round the horizon) and altitude (angle above the horizon). These depend on time an the position of the observer. Only positive altitude angles are seen in the sky.
Astronomers prefer to use right ascension and declination. Declination is the latitude where the star passes overhead, and right ascension expresses how many hours the object crosses the meridian after a standard position called the First Point of Aries. The right ascension and declination are preferred because they don't depend on time or the observer's position on the Earth's surface.
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When the earth ocassionally reverses direction is called what motion?
The earth never reverses direction, nor does any other planet. The APPARENT reversal of direction of some other planets, as seen from earth, is called retrograde motion.
What does -243 Earth days rotation of planet Venus mean?
It means that Venus rotates oncefor every243 days on Earth. The minus sign is to show that Venus rotates in the opposite direction from Earth. Venus rotates in aclockwise direction(seen from an imaginary placehigh above the Earth's north pole).
What direction do almost all of the planets travel as they go around the sun?
All the planets revolve around the Sun in a counterclockwise direction, as seen from above the Earth's north pole.
Explain why a total solar eclipse or total lunar eclipse does not occur at least once a month?
We don't get a lunar eclipse (earth obscuring the sun to the moon) or a solar eclipse (moon obscuring the sun to earth) every month, since the alignment of the sun, moon and Earth is not exact enough. The moon sun and earth are not on the exact same plane, so most of the time when the moon passes in front of the sun, it is either too low or too high to cause a solar eclipse. Similar story with the moon passing behind the Earth for a lunar Eclipse.
How will you describe the moon when it is in the general direction of the sun?
The Moon always keeps the same side facing the Earth.So, whatever direction you name, there is some place on the Moon from which the Earth appears in that direction, and if the observer doesn't move to a different place on the Moon, then the Earth doesn't move either. It's always in the same direction. The concept of "Earth rise" or "Earth set" does not apply on the Moon.(This video from Apollo 8 came as the spacecraft was circling the Moon in orbit.)Note that for about half of the Moon's surface (the far side), the Earth is never visible. During the full moon, very little of Earth is illuminated by the Sun, as seen from the Moon.
Why do the heavenly bodies disappear during the day?
Most heavenly bodies disappear during the day because of sunlight and they change their positions all of the time. However, the sun itself is often regarded as a heavenly body and is obviously seen during the day. The moon can often be seen in daylight too. Even some planets can at times be seen before it has got really dark, particularly Venus, which is often seen just after sunset or before sunrise.
How do heavenly bodies affect the earth?
Most heavenly bodies (stars, other planets, etc.) are simply too far away to affect the Earth in any measurable way (with the exception of their light striking the Earth). However, there are two heavenly bodies that exert a very real effect on the Earth: the Moon and the Sun. The Moon's orbit is close enough to Earth for its gravity to affect our planet in one signifigant way. Its large mass is enough to, in effect, pull liquid water away from the Earth slightly. This is what causes the tides. The Sun is the source (indirectly) of all life on Earth. Its radiation gives warmth to the Earth, allowing it to maintain a life-sustaining temperature range. The Sun also serves as an anchor to our planet, its gravity keeping us in a steady, fairly debris-free orbit. With the exception of the occaisional comet or asteroid, the Sun and the Moon are the only two heavenly bodies that affect the Earth.
When the earth ocassionally reverses direction is called what motion?
The earth never reverses direction, nor does any other planet. The APPARENT reversal of direction of some other planets, as seen from earth, is called retrograde motion.
What planet was used to explain retrograde motion?
Retrograde motion is motion in the opposite direction. In the case of celestial bodies, such motion may be real, defined by the inherent rotation or orbit of the body, or apparent, as seen in the skies from Earth.
What is Aristotle's fifth substance?
Aristotle's fifth substance is the quintessence, also known as aether. This concept was believed to be the substance that made up the heavenly bodies and was considered to be eternal and unchanging. It was thought to be superior to the four earthly elements.
Why is Earth in a spherical shape and not a triangle?
The Earth is a sphere because out of all solid bodies a sphere is the most stable shape(assuming all solids to have equal masses and same average density). A sphere is the best suited shape to withstand gravitational attraction of close- together particles, as seen during the formation then attraction of other heavenly bodies. If the Earth were any shape other than a sphere (or an oblate spheroid, which is what the earth actually is) then it would not be able to maintain it's structure and would eventually become spherical due to gravitational pressure.
Information about dates on which certain celestial bodies were seen?
Dates on which celestial bodies were seen
What does -243 Earth days rotation of planet Venus mean?
It means that Venus rotates oncefor every243 days on Earth. The minus sign is to show that Venus rotates in the opposite direction from Earth. Venus rotates in aclockwise direction(seen from an imaginary placehigh above the Earth's north pole).
What direction do almost all of the planets travel as they go around the sun?
All the planets revolve around the Sun in a counterclockwise direction, as seen from above the Earth's north pole.
Which five heavenly bodies are visible to the naked eye?
Aside from the sun and moon, the fiver inner planets (other than the earth) are visible to the naked eye. Mercury, Venus, Mars, Jupiter and Saturn can all be seen at times without the aid of any optics.
How will you describe the moon when its is in the general direction of the sun?
When the moon is in the general direction of the sun as seen from Earth, then we're looking at the part of it that's not illuminated all by the sun, and we see no moon at all.
Explain why a total solar eclipse or total lunar eclipse does not occur at least once a month?
We don't get a lunar eclipse (earth obscuring the sun to the moon) or a solar eclipse (moon obscuring the sun to earth) every month, since the alignment of the sun, moon and Earth is not exact enough. The moon sun and earth are not on the exact same plane, so most of the time when the moon passes in front of the sun, it is either too low or too high to cause a solar eclipse. Similar story with the moon passing behind the Earth for a lunar Eclipse.
