A Comet
<ol style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Lato, Helvetica, Arial, sans-serif; vertical-align: baseline; background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial; list-style-position: inside; list-style-image: initial; color: rgb(34, 34, 34);"><li style="margin: 0px 0px 10px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;"><span class="ib-brac" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;">(</span><span class="ib-content" style="margin: 0px; padding: 0px; border: 0px; font-style: italic; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;"><a href="https://en.m.wiktionary.org/wiki/astronomy" title="astronomy" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">astronomy</a></span><span class="ib-brac" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;">)</span> A <a href="https://en.m.wiktionary.org/wiki/celestial_body" title="celestial body" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">celestial body</a> consisting mainly of <a href="https://en.m.wiktionary.org/wiki/ice" title="ice" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">ice</a>, <a href="https://en.m.wiktionary.org/wiki/dust" title="dust" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">dust</a> and <a href="https://en.m.wiktionary.org/wiki/gas" title="gas" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">gas</a> in a (usually very <a href="https://en.m.wiktionary.org/wiki/eccentric" title="eccentric" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">eccentric</a>) <a href="https://en.m.wiktionary.org/wiki/orbit" title="orbit" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">orbit</a> around the <a href="https://en.m.wiktionary.org/wiki/Sun" title="Sun" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">Sun</a> and having a "tail" of matter blown back from it by the <a href="https://en.m.wiktionary.org/wiki/solar_wind" title="solar wind" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">solar wind</a> as it approaches the Sun.</li><li style="margin: 0px 0px 10px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;">A <a href="https://en.m.wiktionary.org/wiki/celestial" title="celestial" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">celestial</a> <a href="https://en.m.wiktionary.org/wiki/phenomenon" title="phenomenon" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">phenomenon</a> with the appearance given by the <a href="https://en.m.wiktionary.org/wiki/orbiting" title="orbiting" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">orbiting</a> celestial <a href="https://en.m.wiktionary.org/wiki/body" title="body" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">body</a>.</li><li style="margin-top: 0px; margin-right: 0px; margin-bottom: inherit; margin-left: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;">Any of several species of <a href="https://en.m.wiktionary.org/wiki/hummingbird" title="hummingbird" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">hummingbird</a>found in the <a href="https://en.m.wiktionary.org/wiki/Andes" title="Andes" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">Andes</a>.</li></ol><h4 class="in-block" style="margin: 0px; padding: 0.5em 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: 1.3; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Lato, Helvetica, Arial, sans-serif; vertical-align: baseline; background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial; overflow-wrap: break-word; word-break: break-word; display: table; color: rgb(34, 34, 34);"><span class="mw-headline" id="Synonyms" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: middle; background: none; display: table-cell; width: 272px;">Synonyms</span><span class="mw-editsection" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: middle; background: none; display: table-cell;"><a href="https://en.m.wiktionary.org/w/index.php?title=comet&action=edit&section=5" title="Edit section: Synonyms" data-section="5" class="mw-ui-icon mw-ui-icon-element mw-ui-icon-minerva-edit-enabled edit-page" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: 1.5em; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161); position: relative; min-height: 1.5em; min-width: 3.5em; text-indent: -999px; overflow: hidden; width: 3.5em; max-width: 3.5em; display: block;">Edit</a></span></h4><ul style="margin: 0px; padding: 0px 0px 0px 1em; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Lato, Helvetica, Arial, sans-serif; vertical-align: baseline; background-image: none; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial; list-style: square outside; color: rgb(34, 34, 34);"><li style="margin-top: 0px; margin-right: 0px; margin-bottom: inherit; margin-left: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;"><span class="Latn" lang="en" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;"><a href="https://en.m.wiktionary.org/wiki/faxed_star#English" title="faxed star" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none; color: rgb(107, 75, 161);">faxed star</a></span> <span class="ib-brac qualifier-brac" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;">(</span><span class="ib-content qualifier-content" style="margin: 0px; padding: 0px; border: 0px; font-style: italic; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;">rare<span class="ib-comma qualifier-comma" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;">,</span> dialectal</span><span class="ib-brac qualifier-brac" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;">)</span></li><li style="margin-top: 0px; margin-right: 0px; margin-bottom: inherit; margin-left: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;"><span class="ib-brac qualifier-brac" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; background: none;">A <span style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-weight: 700; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(0, 0, 0);">comet</span><span style="color: rgb(0, 0, 0);"> is an icy, </span><a href="https://en.wikipedia.org/wiki/Small_Solar_System_body" title="Small Solar System body" style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(107, 75, 161);">small Solar System body</a><span style="color: rgb(0, 0, 0);">that, when passing close to the </span><a href="https://en.wikipedia.org/wiki/Sun" title="Sun" style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(107, 75, 161);">Sun</a><span style="color: rgb(0, 0, 0);">, warms and begins to release gases, a process called </span><a href="https://en.wikipedia.org/wiki/Outgassing" title="Outgassing" style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(107, 75, 161);">outgassing</a><span style="color: rgb(0, 0, 0);">. This produces a visible atmosphere or </span><a href="https://en.wikipedia.org/wiki/Coma_(cometary)" title="Coma (cometary)" style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(107, 75, 161);">coma</a><span style="color: rgb(0, 0, 0);">, and sometimes also a </span><a href="https://en.wikipedia.org/wiki/Comet_tail" title="Comet tail" style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(107, 75, 161);">tail</a><span style="color: rgb(0, 0, 0);">. These phenomena are due to the effects of </span><a href="https://en.wikipedia.org/wiki/Solar_radiation" title="Solar radiation" class="mw-redirect" style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(107, 75, 161);">solar radiation</a><span style="color: rgb(0, 0, 0);"> and the </span><a href="https://en.wikipedia.org/wiki/Solar_wind" title="Solar wind" style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(107, 75, 161);">solar wind</a><span style="color: rgb(0, 0, 0);"> acting upon the nucleus of the comet. </span><a href="https://en.wikipedia.org/wiki/Comet_nuclei" title="Comet nuclei" class="mw-redirect" style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(107, 75, 161);">Comet nuclei</a><span style="color: rgb(0, 0, 0);">range from a few hundred metres to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times the Earth's diameter, while the tail may stretch one </span><a href="https://en.wikipedia.org/wiki/Astronomical_unit" title="Astronomical unit" style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(107, 75, 161);">astronomical unit</a><span style="color: rgb(0, 0, 0);">. If sufficiently bright, a comet may be seen from the Earth without the aid of a telescope and may </span><a href="https://en.wikipedia.org/wiki/Subtended_angle" title="Subtended angle" style="margin: 0px; padding: 0px; border: 0px; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; color: rgb(107, 75, 161);">subtend</a><span style="color: rgb(0, 0, 0);"> an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures.</span></span></li></ul>