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bmpbmp
2004-Sep-29, 07:03 PM
According to this tomorrow is the closest approach.

http://neo.jpl.nasa.gov/cgi-bin/db_shm?rec=4179

Today 0.0109au
tomow 0.0105au

I thought it was today

ToSeek
2004-Sep-29, 07:11 PM
That's at midnight at the start of the respective days. Reduce the interval time down to hours, and you'll see that the distance goes down to .0102 for today before going back up again. Note also the warning about accuracy:


The applet was implemented using only 2-body methods, and hence should not be used for determining accurate long-term trajectories (over several years or decades) or planetary encounter circumstances. [Emphasis mine.]

Grizzly
2004-Sep-29, 07:13 PM
The site also says:


Note: Make sure you have Java enabled on your browser to see the applet. This applet is provided as a 3D orbit visualization tool. The applet was implemented using only 2-body methods, and hence should not be used for determining accurate long-term trajectories (over several years or decades) or planetary encounter circumstances. See the "High-Accuracy Ephemeris" link in middle of the page to do this.


But be that as it may, I think that closest approach might occur this afternoon/evening here in North America, which is already Sept. 30th in Grenwich.

----
Catapultam habeo. Nisi pecuniam omnem mihi dabis, ad caput tuum saxum immane mittam
I have a catapult. Give me all your money, or I will fling an enormous rock at your head

bmpbmp
2004-Sep-29, 07:17 PM
ok so the closest approach hasent happened yet then I thought it was at around 8:37am eastern time

ToSeek
2004-Sep-29, 07:22 PM
ok so the closest approach hasent happened yet then I thought it was at around 8:37am eastern time

Around 9:35 EDT (http://www.sciencedaily.com/releases/2004/09/040929105022.htm), or 1335 UT. So it's happened already.

dummy
2004-Sep-29, 07:26 PM
It can't have. The world didn't end :-?

bmpbmp
2004-Sep-29, 07:36 PM
Someone slap me but that means the jpl simulator is in a time zone that is already the 30th right

#-o

Swift
2004-Sep-29, 07:39 PM
It can't have. The world didn't end :-?
Actually it did and was just replaced immediately by an identical one. Didn't you get the e-mail? :wink:

ToSeek
2004-Sep-29, 07:46 PM
Someone slap me but that means the jpl simulator is in a time zone that is already the 30th right

#-o

No. It will be the next day (Universal Time) at 5 pm JPL (Pacific Daylight) time. As I write this, it's 12:45 pm PDT.

bmpbmp
2004-Sep-29, 07:50 PM
ok I dont understand so if it is actually on the 30th then so the closest aprouch is left to come...

Grizzly
2004-Sep-29, 08:09 PM
Nope, the position is as of a certain time on the day displayed. . The closest is actually as Toseek said, .102 and that occurred some time today AFTER the time displayed on the applet. One location per day.

----
Abutebaris modo subjunctivo denuo
You've been misusing the subjunctive again

frogesque
2004-Sep-29, 08:22 PM
Nope, the position is as of a certain time on the day displayed. . The closest is actually as Toseek said, .102 and that occurred some time today AFTER the time displayed on the applet. One location per day.

You mean it missed us? Can I come out from under the table now?

ToSeek
2004-Sep-29, 08:30 PM
ok I dont understand so if it is actually on the 30th then so the closest aprouch is left to come...

It is not actually on the 30th. Grizzly was wrong about that. The closest approach was at 2004-September-29 (today) at 1335 UT, or around 9:35 am EDT, or around 6:35 PDT.

If you go back to the applet and set the interval to hours rather than days (using the listbox just to the right of the bottom of the "Date" button that says "1 Day" by default), then step through today, hour-by-hour, you'll see that the applet roughly agrees with this, assuming that the applet is using UT.