[ExI] Milky Way escape velocity

[spike]

From: extropy-chat-bounces at lists.extropy.org
[mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of Stefano Vaj
Sent: Tuesday, May 01, 2012 4:48 AM
To: ExI chat list
Subject: Re: [ExI] Milky Way escape velocity

 

On 30 April 2012 22:49, BillK <pharos at gmail.com> wrote:

We recently mentioned the velocity required to escape the Milky Way
galaxy - over 1 million miles per hour.



Million? miles?! hour? .-- 
Stefano Vaj

 

 

>.BOTECs in round numbers that I can recall, the distance from the sun to
the center of the Milky Way is about 27,000 years.

spike

 

 

>.I don't know where I went wrong, but this calc feels like it is off an
order of magnitude to the low side.  I think escape velocity from here is
more like 400 km/sec.  What did I do wrong?

 

 

Doh!  Forgot to multiply by 2 pi.  So the tangential velocity out here is
more like 600 micro-c or about 200 km/sec and escape velocity is more like
300 km/sec.  That sounds more like it.  that 40 km/sec scared me: we might
wander close enough to something massive and get kicked off the star island.

 

spike

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