Weather permitting, this month observers in our region will experience two eclipses. The first to occur is a total lunar eclipse on Oct. 8, followed by a partial solar eclipse a couple of weeks later on Oct. 23. On top of that is the encounter between Mars and Comet C/2013 A1 (Siding Spring) discussed in last month's installment.
Each of the upcoming eclipses is unique. The lunar eclipse will be ongoing at sunrise, whereas the solar eclipse takes place at sunset.
First an obligatory yet important warning about solar observing. Viewing the sun without proper filtration — with or without a telescope or binoculars — can cause serious and permanent eye damage. Read on to learn where to view the solar eclipse safely with the help of local amateur astronomers.
All eclipses occur in stages over the course of several hours. The main stages of a lunar eclipse are penumbral, umbral and totality. These occur as the moon, which is traveling in orbit about the Earth, passes through various elements of the Earth's shadow cast by the sun into space. When the moon reaches the outer fringes of the shadow's penumbra, a penumbral phase occurs. When the moon begins passing through the umbra, the umbral phase occurs, which is typically referred to as the "partial eclipse" phase. Only when the entire moon is fully engulfed in the umbra is the eclipse can the eclipse be referred to as a "total" eclipse.
For a more in-depth discussion of the anatomy of a lunar eclipse, refer to the April issue in the Star Points online archive at carrollcountytimes.com.
On the morning of Wednesday, Oct. 8, the moon will be full. The penumbral phase starts about three hours before sunrise, although no darkening of the moon may be visible for another 30 minutes or so. The very dramatic partial eclipse starts at 5:15 a.m. as the umbral shadow sweeps across the moon. Totality begins at 6:24, during morning twilight.
The sun rises at 7:11 a.m., 16 minutes past mid-eclipse, followed 5 minutes later by moonset. Thus, it is theoretically possible for a few moments to view both the eclipsed full moon and the sun together above an unobstructed horizon. This is harder than it sounds as the moon will be faint — after all, it is totally eclipsed — as well as extremely low on the horizon where the atmosphere, at its thickest, will dim the moon's light.
The following list is a summary of the events for the Oct. 8 lunar eclipse. The eclipse events are from Guy Ottewell's Astronomical Calendar 2014. The sunrise and moonset events are for Westminster from the U.S. Naval Observatory.
Oct. 8 total lunar eclipse event and time, EDT a.m.:
A public viewing of the lunar eclipse with members of the Westminster Astronomical Society (WASI) will take place at the Soldiers Delight Natural Environmental area near Owings Mills in Baltimore County. The event runs from 5 to 8 a.m. on Oct. 8.
The next great event of the month is the sunset partial solar eclipse on Thursday, Oct. 23rd. It is the opposite of the partial solar eclipse in October 2013. The 2013 eclipse was in progress at sunrise, whereas this year's October eclipse occurs at sunset.
The following eclipse information comes from NASA's Goddard Space Flight Center. The sunset information is from the U.S. Naval Observatory.
Oct. 23 partial solar eclipse event and time, EDT p.m.:
The sun will set before maximum eclipse occurs for Westminster. In other words, the horizon will block our view of maximum eclipse.
As far as safe viewing goes, there are safe solar observing filters sold by astronomy vendors. Welders glass with #14 density is also considered safe — but only for naked eye viewing. Another safe observing method involves projecting an image using a small telescope or binoculars, and viewing the projected image — not looking through the telescope and binoculars. A small pinhole in a card will also produce a projected image, although it will be rather small.
Perhaps the best and safest way is to view the partial solar eclipse with WASI members at Soldiers Delight on Thursday, Oct. 23, from 5 to 7 p.m.
Finally, the encounter between Mars and Comet Siding Spring occurs on Oct. 19. The best views will be from Mars where a number of spacecraft are preparing to observe the passage and detect any atmospheric effects from the passing comet. The comet was closest to Earth in late September, but was poorly placed for observing in Earth's northern hemisphere.