Moving Earth out of orbit

[Grey]

@bob_2

Yet we worry about a couple of degrees of global warming?

No, we worry about a global energy equilibrium being rapidly moved in a single direction.

[Mangetout]

@Stranger_On_A_Train

“…a few thousand kilometres nearer or further from the sun” is not going to significantly change the thermodynamic state of the Earth, and even a few million is not going to make the planet uninhabitable. The sun goes through phases in variation of irradiance and temperature.

Stranger

Do those phases oscillate about some sort of consistent mean?

[Isilder]

@Jonathan_Chance

Two things:

1. What is the amount of energy required to move the Earth in such a manner?

The escape velocity at earth’s distance is about 42 km/second

From Escape velocity - Wikipedia

The earth is currently at 30 km/sec
The cheapest way is to boost the earths mass up 12 km/second pro-grade (directly in the line of the orbit - actually instantaneous pro-grade… as you apply the acceleration you keep it in the actual direction of movement. ) … Its more expensive to do it by applying the force in some other direction than pro-grade…
Your other question sure reduce the mass of the sun to make the escape velocity (kinetic energy) lesser… changes the orbit of the earth too

[eburacum45]

When the Sun leaves the Main sequence it will star losing mass comparatively rapidly, due to a vastly increased solar wind. Some estimates say that this loss will be enough to move the Earth’s orbit out beyond the edge of the Sun’s red giant phase; others aren’t so sure.
http://www.astronomy.ohio-state.edu/~pogge/Lectures/vistas97.html

[Quartz]

@eburacum45

When the Sun leaves the Main sequence it will star losing mass comparatively rapidly, due to a vastly increased solar wind. Some estimates say that this loss will be enough to move the Earth’s orbit out beyond the edge of the Sun’s red giant phase; others aren’t so sure.
The Once & Future Sun

By that stage the Earth will have lost its magnetic field due to cooling of the core, so it may no longer have an atmosphere.

[Blue_Blistering_Barnacle]

@Quartz

By that stage the Earth will have lost its magnetic field due to cooling of the core, so it may no longer have an atmosphere.

Well, that would take care of the “season’s issue”. You should collect $3.

[XT]

[quote=“Jonathan_Chance, post:20, topic:757193”]

Two things:

1. What is the amount of energy required to move the Earth in such a manner?
   From here:

The escape velocity from the Sun at the vicinity of the Earth is about 42 kilometers per second. You need to subtract the Earth’s orbital velocity from that (assuming you push in the direction the Earth is already travelling to save energy). So the energy needed to accelerate the Earth up to escape velocity from the Sun is:

4.457×1032J

  (joules) - see (Wolfram Alpha calculation)

To understand this huge number, let’s convert it to some other forms:

It is 13.4 days

of the Total Solar Energy output - see (Wolfram Alpha calculation)
and is the energy obtained if you convert 5×1015 kg
(kilograms) of mass to energy - see (Wolfram Alpha calculation)
To understand this huge mass, it is equivalent to the mass of the all the humans on the planet Earth times 10,000

• see (Wolfram Alpha calculation)

I suppose if you were working very long time scales and could engineer some sort of mass that would stay at a constant distance from the Earth you could, eventually, shift the orbit outward…but we’d probably be talking millions of years (or 10’s of millions of years), and today there is no practical way to even start working on something like that…especially if we were wanting to live through the experience.

[eburacum45]

Note that you wouldn’t have to accelerate the Earth to escape velocity in order to move it outwards by a few miilion kilometres. Although the energy required would still be vast.

According to current theories the ice ages on our planet are significantly affected by minor changes in the eccentricity of our orbit; changing the shape of our orbit artificially would certainly cause some very significant changes in our climate.

[dtilque]

@Jonathan_Chance

2. Would the sun losing mass lower its gravity and therefore slip Earth into a wide orbit in the first place?

This is happening right now, but the rate of solar mass loss is so low that it’s pretty negligable. AIUI, the Earth is currently moving away from the Sun about 15 cm/year, but most of that is due to tidal drag.

[Gilbert1984]

@Senegoid

You need but a long enough lever and a place to stand.

(Well, you need a fulcrum too. Maybe you can use the moon, or maybe Mars, for that.)

Obligatory - possobly NSFW, definitely Not Safe For Humanity

[Chronos]

…I fail to see the relevance of that image to anything in the quoted post or to the thread in general.

[Quartz]

There used to be a website that showed the effect of a passing star on the inner planets. I can’t find it now.

[Leo_Bloom]

@dtilque

This is happening right now, but the rate of solar mass loss is so low that it’s pretty negligable. AIUI, the Earth is currently moving away from the Sun about 15 cm/year, but most of that is due to tidal drag.

How is this made manifest in the elliptical orbit?

[Andy_L]

@Quartz

There used to be a website that showed the effect of a passing star on the inner planets. I can’t find it now.

This one ROGUE STAR ?

[dtilque]

@Leo_Bloom

How is this made manifest in the elliptical orbit?

Not really sure. The annual increase (15 cm/year) was calculated by a couple Russians (Gregoriy A. Krasinsky and Victor A. Brumberg) using (I think) timing of comunications to interplanetary probes. This paper says that it is probably due to tidal drag. I’m going to guess that it mainly shows up in a change in the semi-major axis.

[Blue_Blistering_Barnacle]

@dtilque

Not really sure. The annual increase (15 cm/year) was calculated by a couple Russians (Gregoriy A. Krasinsky and Victor A. Brumberg) using (I think) timing of comunications to interplanetary probes. This paper says that it is probably due to tidal drag. I’m going to guess that it mainly shows up in a change in the semi-major axis.

Semi-major- does that mean the orbit becomes more elliptical with time?

[dtilque]

@Blue_Blistering_Barnacle

Semi-major- does that mean the orbit becomes more elliptical with time?

It would if my guess were right. But after thinking it over, I realized that it’s wrong. Since tidal drag is a slow continuous process, it should show up as an increase everywhere along the orbit.