Questions regarding the planet on which humans live, the third planet from the sun.

learn more… | top users | synonyms

-3
votes
0answers
30 views

Radius and velocity of Earth's orbit around the Sun [closed]

How do you find the radius and velocity of Earth's orbit around the Sun?
-3
votes
2answers
60 views

How dense would planet earth have to be to have the same gravity as Jupiter?

I was reading this question about how small could a planet be while having earth-like gravitational pull. This got me thinking, how dense would planet Earth have ...
5
votes
4answers
627 views

Did we ever actually see the earth revolving around the sun? Is the geocentric model completely disproved?

Did we ever actually see the Earth revolving around the Sun? Also, is the geocentric model completely disproved or was it sidelined because the heliocentric model made things easier to understand? ...
0
votes
1answer
28 views

Precessing of the Earth

It's been known that the Earth's axial tilt varies from 22.5 to 24.5. Does this result in a wobbling while the value of the tilt varies about these two limits? If so, how does it affect the mechanics ...
2
votes
1answer
47 views

Why does Mars' experience an 'ice age' at high axis obliquity, when Earth experiences an ice age at low axis obliquity

This paper here goes into some detail about how Mars' experiences its own form of 'ice ages' on a quasi periodic basis driven by the wobbling of its axis. The main mechanism outlined is that the ...
-3
votes
2answers
80 views

earth is spherical , does it mean the ground on earth is like a ball? [closed]

I know earth is spherical in shape. Does this means earths atmosphere is spherical in shape or the ground/(land+water combined) is in spherical shape. I have some doubts if the second is true. ...
5
votes
2answers
137 views

Tide on the Moon

If the Earth's Moon had a water ocean of depth 2-4 Km, how high would the tides rise due to the Earth's gravity? (Just a hypothetical question.)
9
votes
2answers
265 views

Why is the Moon receding from the Earth due to tides? Is this typical for other moons?

After reading the Q&A Is the moon moving further away from Earth and closer to the Sun? Why? about the tides transferring energy to the Moon and pushing it from Earth, I have a question: How is ...
5
votes
2answers
82 views

Meteorites bring water

The latest information suggests that Earth's water came from Meteorites . The Moon was also bombarded by Meteorites and yet it has no water. Is this because it lacks an atmosphere and its water was ...
0
votes
2answers
75 views

Near-future astronomic events that could threaten Earth

What kinds of astronomical events can pose a serious threat to life on Earth in the near future (1000-10,000 years). If there are none in the near future, when is the soonest event that is predicted ...
7
votes
1answer
152 views

As days get longer, why isn't the added daylight split evenly between sunrise and sunset?

I have a basic understanding of the sinusoidal relationship of the rate of change of daylight as the year goes on. But it seems intuitive that the changes should be equally split between sunrise and ...
9
votes
6answers
1k views

Why doesn't Earth's axis change during the year?

My understanding is that the Earth's axis points in the same direction in space during its entire orbit around the sun. And this is what causes our seasons. My question is why doesn't the axis follow ...
1
vote
1answer
35 views

What is the boundary in the atmosphere seen in this video?

This video, which shows time-lapse views of Earth from the ISS, consistently shows some sort of hard boundary in the atmosphere, below which there seems to be significant reflection from sunlight ...
4
votes
1answer
86 views

How bright is the full Earth during the lunar midnight?

At lunar midnight (i.e. the new moon as seen from Earth), the Earth is in its full phase with its entire disk in sunlight, and it is the brightest object in the lunar sky. How bright is it, and how ...
17
votes
2answers
3k views

Does the Earth have another moon?

I was just wondering what are the chances that there is a small object (say less than 1 km but more than few meters) that orbits the Earth but has remained undetected by us? Are we actually ...
11
votes
1answer
249 views

If the moon wasn't receding from Earth, what would be the impact on the weather and tides?

Moon is slowly receding from Earth, which means that after its formation it was much closer to the Earth than now. How would weather look like if it wasn't receding at it would be now as close as at ...
2
votes
1answer
86 views

Look up current positions and velocities of solar system objects

I am working on an orbital dynamics code and, for fun, I would like to model the Sun-Earth-Moon system with my code. I can look up the masses of each object just fine, as well as average distances ...
1
vote
2answers
84 views

What is the orbit of Earth around the Sun?

According to wikipedia and other sources, a planet and a star always move in a circular orbit around the common center of mass of the both bodies, in case of Earth and sun, this center of mass lies ...
4
votes
2answers
143 views

What would happen if we put a small part of White Dwarf or Neutron Star on Earth?

I would know what would happen if we put a small part (let me assume 1 cm$^3$) of White Dwarf or Neutron Star on ...
8
votes
2answers
162 views

Could Venus be a source of Earth's water?

I've watched documentaries about the solar system, where it is suggested that Venus once had oceans of liquid water similar to those that cover most of Earth today. Venus is now in a period of ...
-1
votes
1answer
106 views

Distance between Earth and where The Big Bang's happened? [duplicate]

The universe is around 13.8 billion years old. We know how fast the light is. We also know how fast our galaxy moving around inside observable universe. Is it possible to calculating distance ...
3
votes
2answers
121 views

Could the Philae comet lander be recharged by laser?

Could the Philae comet lander be recharged with a laser (or possibly many lasers) from earth? My thought would be to aim one or more powerful lasers from earth at the Philae lander to recharge it ...
15
votes
1answer
902 views

Can you see man-made lights on the dark side of the Earth from the surface of the moon with the naked eye?

This question is prompted from a comment on this answer: Could a person on the surface of the moon see man-made lights on the dark side of the Earth with the naked eye? If not, how much magnification ...
3
votes
1answer
399 views

How likely and severe is the threat of a gamma ray burst to earth?

In the National Geographic article: http://news.nationalgeographic.com/news/2009/04/090403-gamma-ray-extinction_2.html it is suggested that a gamma ray burst likely caused a mass extinction in earth's ...
2
votes
1answer
72 views

How does this strategy for chasing the sunset work?

In Randall Munroe's What If? blog he tackles this question: What is the longest possible sunset you can experience while driving, assuming we are obeying the speed limit and driving on paved ...
-3
votes
1answer
73 views

Why does Earth enjoy a significantly longer time as a habitable planet as compared to Mars or Venus? [closed]

On a related note, why didn't Venus remain habitable for longer than it did? Is the current hypothesis as to the time when Venus's atmosphere became hostile and what event triggered it, proven true?
4
votes
2answers
414 views

Will Earth lose the Moon before the Sun goes into supernova?

Ive read on some sites and saw on youtube videos that the moon is getting away from earth by 1-3 cm a year. Is this enough to make the Earth lose the Moon before the Sun goes into Supernova? Im ...
4
votes
1answer
171 views

From what distance can one object influence gravity of another object?

Each object in the universe has its own gravitational influence on all other objects in the universe. What distance do they have to be from each other to create only one gravitational influence? ...
6
votes
2answers
932 views

Does the Moon's magnetic field affect Earth's magnetic field?

I wanted to ask a question; it's simple but I cannot find any possible and perfect solution. Earth has poles, North and South. By which we can get directions using a compass or a needle compass, but ...
13
votes
2answers
2k views

What is the distance that the Moon travels during one orbit around the Earth?

Also, does it always take the same amount of time, or does it fractionally differ on each revolution?
6
votes
1answer
101 views

Why does this graph for sunlight intensity on land has a steeper slope during sunrise as compared to sunset?

I got this image while checking weather data for a city in North India using Mathematica's Wolfram Alpha query I noticed one feature in the graph which i could not explain . Why does the encircled ...
2
votes
1answer
94 views

What causes the bright white area in this photo of the earth?

Regarding the photo of the earth described here, I know that the green tinge on the left hand side is to do with the aurora borealis. What's causing the bright white light on the right hand side?
-5
votes
3answers
170 views

I know when the human history ends. Or not?

If you think that we born on 1920...2000 and knows that the sun will explode 4 to 5 billion years from now. you will say that the time is a strange thing. I can not say that i will die before i know ...
1
vote
2answers
204 views

How to calculate right ascension of Greenwich? [closed]

If I know specific time, t0, how can I calculate RA of Greenwich?
2
votes
2answers
67 views

Birthdate differences calculation relative to earths orbit duration

I have got a question as i am trying to figure out what the real difference between the birthdate of my friend and me is. I am born on 1983 6th February 7 am. My Friend is born on 1984 7th February 1 ...
1
vote
1answer
46 views

the length of second, minute or hour, what defines the time of exo planetary bodies

we measure time based on earth and earth mass\gravity plays a role in the measurement ? so how and what would be time if not earth time on other exo planets since they will be having different ...
6
votes
2answers
139 views

Is it possible for a person to not see the new moon at different places on earth?

It is known that theoretically we see the same moon phase everywhere on the earth, but practically I see that people are unable to observe the 0.8% waxing crescent at different places on earth. This ...
2
votes
1answer
138 views

Hour angle sunrise calculation problem

I am trying to program a sunrise/sunset calculator using this formula tutorial. If you follow the steps, eventually you get to this formula for "H" (the "hour angle"): $H = \arccos( [\sin(-0.83) - ...
10
votes
3answers
415 views

Is it a coincidence that both the sun and moon look of same size from earth?

The sun is huge when compared to moon. Despite the huge difference in their size and distance from earth, Is it purely coincidental that they both look almost the same from earth?
2
votes
2answers
2k views

Why don't stars move in the night-sky as the moon does?

I want to know why don't we see a change in the position of stars during the night while we do see a change in the position of the moon. I've checked other online sources and some answers say that it ...
2
votes
1answer
129 views

Connection between Earth, Moon, Theia, and astroid belt?

Are there other fragments aside from the Moon that resulted from the collision of Earth and "Theia" (as it's called in recent main-stream press stories)? And if not, why not? And what happened to ...
8
votes
6answers
739 views

Why don't we have 2 Summers and 2 Winters?

Due to Earth's elliptical orbit, its distance from Sun varies by almost 5 million Kilometers (147 million Kilometers at closest point & 152 million Kilometers at farthest point, i.e. almost 3% of ...
3
votes
2answers
106 views

seasons elongating and shortening

I have heard of years with longer summers and winters and shorter springs and falls and vice versa because of a change in the earths axis. Is this from the procession that causes the season switch ...
3
votes
3answers
201 views

Inclination of planets

Why do the planets have roughly the same inclination with respect to Earth? Looking at the inclinations, which I got from http://www.astronomynotes.com/tables/tablesb.htm , we see that Mercury has ...
4
votes
2answers
256 views

What mechanism causes oscillations of the solar system's orbit about the galactic plane?

In a recent paper (news release here) Lisa Randall and Matthew Reece propose that a dark matter disk coinciding with the galactic plane together with the solar system's oscillations through the ...
2
votes
2answers
188 views

Is it possible to move a planet out of its orbit? At least a lighter planet?

As observed by many researches our sun will be exhausted in a distant future. So anyone thinks driving our planet (or any planet) closer to the sun for more light and heat is a solution for the life ...
4
votes
2answers
182 views

Can I look at the sky and find the day of the week?

Suppose I wake up from a coma on a desert island in the 19th century (i.e. we already use the Gregorian calendar but have no satellites yet). I have a clear view of the sky and a couple of days to ...
4
votes
1answer
159 views

“If earth had rings like Saturn”: A few further thoughts on the consequences

I came across this video recently where artists depicted what it would look like if Earth had rings like Saturn. http://www.wimp.com/earthrings/ Please note: The video contains already some ...
1
vote
1answer
43 views

Can the next possible ice age be projected based upon the Milankovitch cycle?

The Milankovitch cycle describes the collective effects of changes in the Earth's movements upon its climate[.] By this theory, the Earth is now experiencing an interglacial. By the theory, ...
11
votes
2answers
517 views

Why do stars appear to twinkle?

Sometimes at night you will look up to the stars and they will appear to twinkle, getting brighter and darker in bursts. Why does this happen? Is this because of our atmosphere? Would they twinkle ...