Is Pluto A Planet?

[April_Rose]

Sorry, what? The moon is not a planet... and while the earth orbits the sun the moon orbits the earth. They certainly don't have the same center of gravity...

Yeah you're right come to think about it. I do believe that there is less gravity on the moon than on earth.

 

[d taylor]

What is? Pluto?

You have a bunch of scientific answers.

I gave you a Biblical answer.

 

[Friedrich Rubinstein]

Yeah you're right come to think about it. I do believe that there is less gravity on the moon than on earth.

There is 1/6 of the earth's gravity on the moon Which means a person of 72kg on earth would show 12kg on a scale on the moon.

 

[April_Rose]

You have a bunch of scientific answers.

I gave you a Biblical answer.

Yeah but you weren't telling me what exactly was a star,.. I'm guessing you meant Pluto but I was only asking you to be more specific.

 

[April_Rose]

And wait how can Pluto be a star? Aren't all stars hot? Pluto is the farthest whatever from the sun. It clearly isn't hot.

 

[Friedrich Rubinstein]

And wait how can Pluto be a star? Aren't all stars hot? Pluto is the farthest whatever from the sun. It clearly isn't hot.

When I hear "star" I first think of them emitting light, but yeah... they are also hot

 

[April_Rose]

When I hear "star" I first think of them emitting light, but yeah... they are also hot

Also waiting for a Bible verse to be quoted on where it mentions Pluto as a star.

 

[JackRT]

That doesn't make sense though. I mean not about the moon in particular, (and I think I remember reading somewhere that it is actually an asteroid but I could be wrong about that) but think about this. There are many different solar systems out there and many different planets that don't orbit the earth,.. so why would it make a difference in our solar system if Pluto or planet X or whatever didn't orbit the earth?

Actually the earth and the sun also rotate about a common centre of gravity but the sun is so much more massive than the earth that the centre of gravity is actually within the sun but not at its centre. In the case of all the other planets that have satellites those satellites are very much smaller than their primary and some are actually larger than our moon. If you know astronomy and physics it makes perfect sense that the earth and the moon are a double planet system. Don't get hung up on common terminology just understand the science. If you don't know the science then perhaps it is best to say nothing.

 

[Friedrich Rubinstein]

Actually the earth and the sun also rotate about a common centre of gravity but the sun is so much more massive than the earth that the centre of gravity is actually within the sun but not at its centre. In the case of all the other planets that have satellites those satellites are very much smaller than their primary and some are actually larger than our moon. If you know astronomy and physics it makes perfect sense that the earth and the moon are a double planet system. Don't get hung up on common terminology just understand the science. If you don't know the science then perhaps it is best to say nothing.

If you mean that the moon influences the earth's orbit - yes, of course. But when you speak about orbits in astronomy you look at actual orbits and not the wiggling of a planet caused by its moon(s).

 

[Occams Barber]

If you mean that the moon influences the earth's orbit - yes, of course. But when you speak about orbits in astronomy you look at actual orbits and not the wiggling of a planet caused by its moon(s).

No Friedrich, @JackRT is referring to the 'barycentre'. This is not the same as Earth's centre of mass. This quote might help:

Earth and the Moon orbit about their barycentre (common center of mass), which lies about 4,600 km (2,900 mi) from Earth's center (about 72% of its radius).

Orbit of the Moon - Wikipedia​

OB

 

[Hans Blaster]

There is 1/6 of the earth's gravity on the moon Which means a person of 72kg on earth would show 12kg on a scale on the moon.

Actually, that isn't fully correct.

Scales do measure weight and with g_moon = g_earth/6 the weight would be 1/6 that measured on Earth. Weight = gravity * mass (i.e., it's a force).

A kilogram is the unit of mass and the mass of a person does not change depending on the local gravity. This person would be 72 kg on Earth, on the Moon, or in orbit.

Regular bathroom scales measure force, or specifically weight. Because we are used to measuring objects in kg, these scales actually report not the measured weight, W, but rather W/g, a mass unit. The 72 kg person weighs 706 Newtons (the force unit) on Earth (with g_earth = 9.8 m/s^2), on the Moon the weight of the same person would be 117 N. If you measured that person with an Earth scale which reports W_moon/g_earth you would indeed get 117 N/ 9.8 m/s^2 = 11.9 "kg".

If you used one of those physicians balance beam scales (the ones with the sliding weights), you are directly measuring mass by balancing two weights against each other. With that scale it would (correctly) read 72 kg on the Moon and on the Earth. (It would not work in orbit as there isn't the gravitational acceleration pulling on both masses to properly balance.)

 

[April_Rose]

Actually, that isn't fully correct.

Scales do measure weight and with g_moon = g_earth/6 the weight would be 1/6 that measured on Earth. Weight = gravity * mass (i.e., it's a force).

A kilogram is the unit of mass and the mass of a person does not change depending on the local gravity. This person would be 72 kg on Earth, on the Moon, or in orbit.

Regular bathroom scales measure force, or specifically weight. Because we are used to measuring objects in kg, these scales actually report not the measured weight, W, but rather W/g, a mass unit. The 72 kg person weighs 706 Newtons (the force unit) on Earth (with g_earth = 9.8 m/s^2), on the Moon the weight of the same person would be 117 N. If you measured that person with an Earth scale which reports W_moon/g_earth you would indeed get 117 N/ 9.8 m/s^2 = 11.9 "kg".

If you used one of those physicians balance beam scales (the ones with the sliding weights), you are directly measuring mass by balancing two weights against each other. With that scale it would (correctly) read 72 kg on the Moon and on the Earth. (It would not work in orbit as there isn't the gravitational acceleration pulling on both masses to properly balance.)

Math is and was one of my worst subjects.

 

[Hans Blaster]

Math is and was one of my worst subjects.

Good thing this is physics.

 

[mama2one]

school is no longer including pluto as a planet
so it must not be one

kids are lucky, one less to remember, lol

 

[April_Rose]

Good thing this is physics.

They're both closely related.

 

[Shemjaza]

school is no longer including pluto as a planet
so it must not be one

kids are lucky, one less to remember, lol

There's a new phrase to remember the planets too.

When I was a kid we had:
My very earnest mother just sits up near pop

Now they have:
My very excellent mother just serves us nachos

 

[Shemjaza]

First scientists were saying that it was, then they said that it wasn't,.. after that they were saying that they were right the first time,.. so what are we on now? Is it considered a planet or not? And why or why not?

Think of the Solar system as having three kinds of planets:

Rocky planets, with clear obits and not necessarily an atmosphere
Mercury, Venus, Mars, Earth

Gas giants, large lower density with huge, huge atmospheres of light gases
Jupiter, Saturn, Uranus, Neptune

And finally dwarf planets, smaller loose planets without clear orbits,
Pluto, Charon, Ceres... and potentially hundreds of others.

 

[Shemjaza]

The moon is one partner in a double planet system. The moon does not orbit the earth but we both orbit a common centre of gravity.

The feels silly to me... technically we don't orbit the sun either, since we both orbit the centre of gravity of the Earth Sol system. (It's just functionally almost identical to the centre of mass of the Sun alone.)

The centre of gravity of the Earth and Luna is inside the Earth so you can just say that the Moon orbits the Earth and be done with it.

(To be on topic, the centre of mass of Charon and Pluto is definitely in between the two dwarfs so it's fair to call them a double planet.)

 

[Strathos]

You have a bunch of scientific answers.

I gave you a Biblical answer.

Pluto isn't mentioned anywhere in the Bible.

 

[fwGod]

Without Pluto the acronym is canceled MVEMJSUNP