"bower list" error messages - node.js

Question

I'm using Windows 7 64-bit. When I execute the command bower list from the command prompt, it shows the following errors:
D:\ng>bower list
bower check-new Checking for new versions of the project dependencies..
bower error Request to https://bower.herokuapp.com/packages/bootstrap fa
iled: 6512:error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol:o
penssl\ssl\s23_clnt.c:787:
Stack trace:
Error: Request to https://bower.herokuapp.com/packages/bootstrap failed: 6512:er
ror:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol:openssl\ssl\s2
3_clnt.c:787:
at createError (C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_modules\bow
er\node_modules\bower-registry-client\lib\util\createError.js:2:15)
at Request._callback (C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_modul
es\bower\node_modules\bower-registry-client\lib\lookup.js:98:29)
at self.callback (C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_modules\b
ower\node_modules\bower-registry-client\node_modules\request\request.js:129:22)
at Request.EventEmitter.emit (events.js:95:17)
at Request.request.emit (C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_mo
dules\bower\node_modules\bower-registry-client\node_modules\request-replay\index
.js:69:33)
at ClientRequest.self.clientErrorHandler (C:\Users\xxxxx.xxxxxxxx\AppData\Ro
aming\npm\node_modules\bower\node_modules\bower-registry-client\node_modules\req
uest\request.js:239:10)
at ClientRequest.EventEmitter.emit (events.js:95:17)
at CleartextStream.socketErrorListener (http.js:1547:9)
at CleartextStream.EventEmitter.emit (events.js:95:17)
at SecurePair.<anonymous> (tls.js:1400:15)
Console trace:
Trace
at StandardRenderer.error (C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_
modules\bower\lib\renderers\StandardRenderer.js:72:17)
at Logger.<anonymous> (C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_modu
les\bower\bin\bower:111:22)
at Logger.EventEmitter.emit (events.js:95:17)
at Logger.emit (C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_modules\bow
er\node_modules\bower-logger\lib\Logger.js:29:39)
at C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_modules\bower\lib\comman
ds\index.js:40:20
at _rejected (C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_modules\bower
\node_modules\q\q.js:797:24)
at C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_modules\bower\node_modul
es\q\q.js:823:30
at Promise.when (C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_modules\bo
wer\node_modules\q\q.js:1035:31)
at Promise.promise.promiseDispatch (C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\
npm\node_modules\bower\node_modules\q\q.js:741:41)
at C:\Users\xxxxx.xxxxxxxx\AppData\Roaming\npm\node_modules\bower\node_modul
es\q\q.js:557:44
System info:
Bower version: 1.3.8
Node version: 0.10.28
OS: Windows_NT 6.1.7601 ia32
Does anyone know what causes this error?