BACK­YARD UNI­VERSE

A lu­nar eclipse

The Covington News - - School Beat -

On Feb. 20 there will be a to­tal eclipse of the moon. It should be a good one and will be the last to­tal we will see for an­other three years.

So, what causes an eclipse? As the moon or­bits the Earth, it passes be­tween the Earth and the sun, block­ing out the sun’s light and pro­duc­ing an eclipse of the sun. Later in its or­bit, the moon goes be­hind the Earth and passes through the Earth’s shadow, pro­duc­ing an eclipse of the moon. A so­lar (sun) eclipse oc­curs at new moon phase and the lu­nar (moon) eclipse oc­curs at full moon.

So why is there not a so­lar and lu­nar eclipse ev­ery month, which is 29.5 days? The an­swer is that the moon’s or­bit is in­clined 5 de­grees to the Earth’s or­bit. This means that most of the time the moon rides above or be­low the sun and Earth’s shadow, but some­times it rides through some or all of the sun and passes through the Earth’s shadow and we see an eclipse.

The lu­nar eclipse on Feb. 20 will be­gin at 8:34 p.m., when the moon starts to en­ter the darker shadow of the Earth. From this point on, the Moon will ap­pear to get smaller as the Earth’s shadow moves across the Moon’s sur­face. Dur­ing the eclipse you can see that the Earth’s shadow on the Moon is curved. The cur­va­ture of the Earth’s shadow was the first proof that the Earth was not flat. The next stage in the eclipse is just be­fore the shadow com­pletely cov­ers the moon, then its sur­face will take on a yel­low­ish-orange or red­dish-orange color due to the Earth’s at­mos­phere bend­ing light from its edges and send­ing it in the Earth’s shadow down to an al­most dark moon. Whether the color is yel­low or red de­pends upon on how deep the moon rides through the shadow and how dirty the Earth’s at­mos­phere is at the time. If there has been a vol­canic erup­tion, the moon may be deep red in color. For this eclipse the color is ex­pected to be yel­low with some orange.

To­tal eclipse will be­gin at 10 p.m. and to­tal­ity will last un­til 10:52 p.m. Af­ter this, the moon will un­cover a lit­tle at a time un­til 12:09 a.m., when we will once again see a full moon. So if you have to get early to go to work, you can watch the first half and know that the sec­ond half is just the first have re­versed.

I will be ob­serv­ing and pho­tograph­ing the eclipse with my Ox­ford stu­dents, but I can’t get too ex­cited be­cause Mother Na­ture can put on some great ce­les­tial shows some­times, but some­times she also hides then with clouds.

Un­til next time, clear and dark skies.

Jim Hon­ey­cutt

Colum­nist

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