<p>Has Chelsea become so trendy even Martians are scouting for co-ops?</p>
<p>A silvery vision of a dozen balloon-like dots hovering in yesterday's clear-blue sky over West 23rd Street in Manhattan had thousands speculating the mysterious objects might be UFOs.</p>
<p>Callers began phoning the NYPD and Federal Aviation Administration at 1:30 p.m. with reports of the strange, silver objects high in the sky.</p>