Searching for list of measurements of moon-earth distance.

[azoulay]

Can someone please help,

I'm searching for daily (or weekly) list of measurements of moon-earth distance.

Seems hard to find on the Internet.

Regards,

Jonathan

 

[ideasrule]

Is there even anybody measuring the Earth-Moon distance on a daily basis? For all practical intents and purposes, including sending spacecraft to the Moon, getting it from the ephemerides is more than accurate enough.

 

[Nik_2213]

These workers seem to be getting the best data: You could contact them...
http://en.wikipedia.org/wiki/Apache_Point_Observatory_Lunar_Laser-ranging_Operation

 

[tony873004]

What dates are you looking for?

 

[azoulay]

What dates are you looking for?

I want to plot the trajectory of the moon for a full year, any year would do.

Regards,

Jonathan

 

[tony873004]

Send the following email to horizons@ssd.jpl.nasa.gov
Put the word job in the subject line.
Within a few seconds, they will email you back with data. It will give you the position and velocity vectors of the Moon (object 301) with respect to the Earth (object 399) every day (TIME_STEP = '1 days') from January 1, 2012 to January 1, 2013. To get distance, take the first 3 numbers for any given day, and use the Pythagorean theorem. For example, your first 3 numbers under January 1, 2012 are

3.980113474770425E+05  4.839373608138232E+04  3.384863277024143E+04

sqr((3.980113474770425E+05)^2 + (4.839373608138232E+04)^2 + (3.384863277024143E+04)^2) = 402368.880944862
So on January 1, 2012 at 00:00:00, the Moon is 402368.880944862 km from Earth.

!$$SOF
EMAIL_ADDR=''
START_TIME = '2012-Jan-01 00:00:00'
STOP_TIME = '2013-Jan-01 00:00:00'
STEP_SIZE = '1 days'
TABLE_TYPE = 'Vector'
REF_PLANE = 'Ecliptic'
CENTER = '@399'
COMMAND= '301'
!$$EOF

 

[Dickfore]

Send the following email to horizons@ssd.jpl.nasa.gov
Put the word job in the subject line.
Within a few seconds, they will email you back with data. It will give you the position and velocity vectors of the Moon (object 301) with respect to the Earth (object 399) every day (TIME_STEP = '1 days') from January 1, 2012 to January 1, 2013.

Notice the title of the thread contains the word MEASUREMENTS. I find it hard there are any for the time period you had specified.

 

[tony873004]

Notice the title of the thread contains the word MEASUREMENTS. I find it hard there are any for the time period you had specified.

I think you're nit-picking the words too much. I read beyond the title of the thread to clarify why he wanted these numbers. In post #5 the he tells us why. The method I've described will provide him all the numbers he needs to accomplish his goal.

 

[azoulay]

Hi tony873004,

This is exactly what I need but for some reason, it doesn't seem to work:

I sent 2 emails:

1- with EMAIL_ADDR=''
and
2-with EMAIL_ADDR='personalmail@---.com'

(of course with the rest of the code you provided)

didn't received any response yet.

Can it take more than one hour?

Regards,

Jonathan

 

[tony873004]

It should take less than 10 seconds, although occassionally it can take a few hours, and occasionally the system is down.
Sorry, I forgot to tell you, format your email as plain text rather than HTML. If that doesn't work, send me a PM with your email and I'll forward the one I received to you.

 

[ideasrule]

If the email method doesn't work, HORIZONS also has a web interface: http://ssd.jpl.nasa.gov/?horizons

 

[azoulay]

The email method worked after converting the email in plain text instead of HTML code.

Thank you so much this is exactly what I was hoping for,

Regards,
Jonathan

 

[azoulay]

I do have two other questions:

1- Which software would be the best to plot the orbit of the moon (with the JPL data) ?

2- Does JPL (or another laboratory) measure on a daily basis the brightness (seen from Earth of course) of the planets in our solar system? If so, is that data available?

Regards,

Jonathan

 

[Dickfore]

2- Does JPL (or another laboratory) measure on a daily basis the brightness (seen from Earth of course) of the planets in our solar system? If so, is that data available?

Do you know what JPL stands for?

 

[azoulay]

Not sure why your asking the question but yes I know: Jet Propulsion Laboratory.

Why are you asking the question ?

Regards,

Jonathan

 

[tony873004]

Do you know what JPL stands for?

It stands for Jet Propulsion Laboratory.

edit: It looks like Azoulay beat me to it :)

I do have two other questions:

1- Which software would be the best to plot the orbit of the moon (with the JPL data) ?

Using the data you collected, you could plot it in Excel. Or, if you have a Windows computer, you can use the program I wrote, Gravity Simulator ( www.gravitysimulator.com ). There you can open one of many solar simulations, focus on the Earth, and watch the Moon go round. The JPL elements are already done for you.

2- Does JPL (or another laboratory) measure on a daily basis the brightness (seen from Earth of course) of the planets in our solar system? If so, is that data available?

Do you need a measurement, or will a computation do? I doubt anyone is actually taking measurements on a daily basis. You could compute it yourself with the data you gathered last week. It's a bit tricky as it involves the flux density at the planets' distance from the Sun, the planets' cross-sectional area, the albedo of the planet, the distance between the planet and the Earth, and the phase of the planet. I believe that JPL Horizons can give you this data too. You'll have to read their documentation to determine how. You could also use a program like Stellarium, which will give you the magnitude of the planet at any given time. Then you could convert magnitude to brightness. I've seen discussions where people pointed out that various sources are not always in agreement as to the magnitude of the planets, but these differences are not very large. By computing it, you can't take into account stuff like Mars' albedo changing due to polar caps dust storms, clouds, or simply brighter regions of the planet rotating into view. But I doubt you're going to find a list of actual measurements.

 

[Dickfore]

Not sure why your asking the question but yes I know: Jet Propulsion Laboratory.

Why are you asking the question ?

Regards,

Jonathan

Do you think jet propulsion has anything to do with astronomical observations?

 

[azoulay]

Hi tony873004, thanks again for your answers.

I was looking for measurements this time.

I wanted to compare the brightness of the planets in correspondence with its distance from earth. I was wondering if there's a direct correspondence between the two.

Regards,

Jonathan

 

[azoulay]

Do you think jet propulsion has anything to do with astronomical observations?

Hi DickFore,

I'm an amateur, I love astronomy. I don't know your background but you seem to know a lot more than me.

Instead of trying to embarrass me with your questions, why don't you just provide me with good answers?

I might not ask the greatest questions but that's just because I don't know a lot. Also, I don't know the whole scope of the research done at JPL. Is there a problem with that ?

If you read Tony873004 reply, he's suggesting that JPL Horizons might provide me with the information I'm seeking about the brightness of stars. So it seems my question was not that stupid after all.

If you care about replying to people, take example on Tony873004 and provide good answers. If you don't have any good answers, please don't waste my time with your embarrassing questions.

Thank you,

Jonathan

 

[Dickfore]

If you read Tony873004 reply, he's suggesting that JPL Horizons might provide me with the information I'm seeking about the brightness of stars. So it seems my question was not that stupid after all.

Well, this is what you had asked:

2- Does JPL (or another laboratory) measure on a daily basis the brightness (seen from Earth of course) of the planets in our solar system? If so, is that data available?

and, when asked whether:

Do you need a measurement, or will a computation do? I doubt anyone is actually taking measurements on a daily basis.

you replied:

Hi tony873004, thanks again for your answers.

I was looking for measurements this time.

So, I guess, no, JPL nor any other agency can not provide you with the information you are looking for.

 

[azoulay]

Mr. DickFore,

Well at least Tony answered my question the best he could and provided me with alternative (computation instead of measurement).

My point is that Tony's replies are all constructive and helpful even if my questions are not that elaborate.

You DickFore, you're not providing answers, you were asking questions that were not constructive nor helpful and I felt you were asking these questions only to embarrass me.

Why do you even care to reply to some questions if you don't have an answer? Like I said in my previous reply, please don't waste my time if you don't have answers for me.

Jonathan