The document provides information about celestial events visible from Earth between September 18-27, 2015. It discusses conjunctions between the moon and planets Saturn and Mars. The full moon on September 27 will be visible for a total lunar eclipse, with the moon passing completely through Earth's shadow. Times for the eclipse phases are provided in Coordinated Universal Time and various US time zones. The eclipse will last over 3 hours with totality lasting 1 hour and 12 minutes, and the moon will appear 13% larger due to its close proximity to Earth.

1. The Sky this Week: September 18-27, 2015
Your daily digest of celestial events coming soon to a sky near you.
By Michael E. Bakich | Published: Friday, September 18, 2015
RELATED TOPICS: LUNAR ECLIPSE | JUPITER | VENUS | MARS | NEPTUNE
In December 2004, Jupiter and the Moon hung close together. On September 18, Saturn will take its turn near
the Moon in the evening sky.
Ronnie Warner
Friday, September 18
The waxing crescent Moon passes 3° north of Saturn this evening, nicely pointing the way to
the glorious ringed planet. Binoculars will offer the best views of this pretty conjunction.
Saturday, September 19
Jupiter passed on the far side of the Sun less than a month ago, but it already has returned to
view before dawn. The giant planet rises about 80 minutes before our star and climbs some 7°
high in the east 45 minutes before sunrise. Shining at magnitude –1.7, it stands out even in
twilight below Venus and Mars. The three morning planets will undergo a spectacular series of
conjunctions during October.
Sunday, September 20
The nearly First Quarter Moon lies close to halfway up in the southwestern sky as darkness
falls. Although our satellite officially reaches First Quarter phase at 4:59 a.m. EDT tomorrow

2. morning, it appears half-lit as it descends toward the western horizon this evening. The Moon
lies on the border between the constellations Ophiuchus and Sagittarius.
Jupiter shines at twilight, but the morning “star” Venus gleams at its brightest of the year September 21, and
will remain a beacon all month.
Astronomy: Roen Kelly
Monday, September 21
This morning, Venus reaches its greatest brilliancy of the year when it shines at magnitude –
4.8. That makes it 17 times brighter than Jupiter, the next-brightest object in the morning sky.
Earth’s sister planet rises before twilight commences. If your observing location is dark enough,
look down and you’ll see that Venus casts a visible shadow. On the 24th, the planet will cross
the border from the constellation Cancer the Crab and move into Leo the Lion.
Tuesday, September 22
Go out around 10 p.m. local time tonight, look toward the northeast, and find the W-shaped
asterism that marks the main part of the constellation Cassiopeia the Queen. Then, using
binoculars, scan about 10° to the east for the famed Double Cluster (NGC 869 and NGC 884).

3. This pair of open star clusters lies in the neighboring constellation Perseus the Hero. From a
dark site, they appear as fuzzy patches to the naked eye. Any optics, especially 10-power
binoculars, really bring out their glory.
Wednesday, September 23
The September equinox occurs at 4:21 a.m. EDT. Most people call this the Autumnal Equinox,
but it’s only the beginning of fall in the Northern Hemisphere. South of the equator, spring is
beginning. What’s happening in the sky is that our Sun, in its annual trek through the
constellations, is crossing the celestial equator (the projection of Earth’s equator into space)
headed south. So, for the next three months, southern latitudes will see our daytime star climb
higher in the sky as it dips lower in the sky each day for northern locations.
In 2008, Mars shone in alignment between Saturn (top) and Regulus (bottom). On September 24, the Red
Planet will slide less than a degree from Regulus.
Rick Stankiewicz
Thursday, September 24
Mars passes 0.8° due north of Regulus, the brightest star in the constellation Leo the Lion.
Regulus was one of the four royal stars to ancient Persian skygazers. They believed one
special star ruled each season. The other three luminaries were Aldebaran in Taurus the Bull,
Antares in Scorpius the Scorpion, and Fomalhaut in Piscis Austrinus.
Friday, September 25
The variable star Algol in Perseus reaches minimum brightness at 8:12 p.m. EDT. You can
start watching it around midevening (it rises in the northeast around 8:30 p.m. local daylight
time). Compare its brightness (magnitude 3.4) to neighboring stars. Then go out tomorrow

4. evening and look again. Algol’s magnitude will have increased to 2.1, so it will be more than
three times brighter than tonight. This eclipsing binary star runs through a cycle from minimum
to maximum and back every 2.87 days. Algol passes nearly overhead shortly before morning
twilight commences.
Saturday, September 26
Neptune stands in the southeast as darkness falls and climbs nearly halfway to the zenith in
the southern sky as midnight approaches. The eighth planet glows at magnitude 7.9, so you’ll
need binoculars or a telescope to spy it. It lies among the background stars of the constellation
Aquarius the Water-bearer. Use medium to high power in your scope because Neptune spans
a tiny 2.3".
The Full Moon slides through the southern part of Earth’s dark umbral shadow the night of September 27/28,
mimicking this eclipse from April 14/15, 2014.
Richard McCoy
Sunday, September 27
Because tonight’s Full Moon is the closest of the year, many people and the media refer to it as
2015’s Super Moon. And while that’s cool, it’s not the most special thing about our satellite this
evening. Indeed, viewers under a clear sky across North America will witness a total lunar
eclipse. The penumbral eclipse starts at 8:12 p.m. EDT. This moment marks when the Moon
enters Earth’s lighter outer shadow. If you don’t notice the start, you won’t be alone. Most
people don’t spot any change to the Moon’s appearance until just before the partial eclipse
begins. That moment happens at 9:07 p.m. EDT. The Moon begins to enter Earth’s dark inner

5. shadow, called the umbra. The Moon is completely in the umbra at 10:11 p.m. EDT. That’s
when totality begins. But relax. Unlike total solar eclipses, whose totalities last a maximum of
7½ minutes, the Moon will remain totally eclipsed for 72 minutes. Mid-eclipse — sometimes
called greatest eclipse — occurs at 10:47 p.m. EDT. From this point, everything about the
eclipse begins to play itself in reverse. Totality ends at 11:23 p.m. EDT. The partial eclipse
ends at 12:27 a.m. EDT, and the entire event comes to a not-so-dramatic conclusion as the
Moon slips out of Earth’s penumbra at 1:22 a.m. EDT. During totality, keep an eye on the
different illuminations on different parts of the Moon. Our satellite doesn’t plow through the
center of Earth’s shadow, but rather passes south of that point. So, the southern end of the
Moon will lie closer to the edge of Earth’s umbra and will appear lighter.
This Week’s Sky at a Glance,
September 18 – 26
By: Alan MacRobert | September 18, 2015
The waxing Moon passes over Saturn and Scorpius at dusk this weekend. The blue 10° scale is about
the size of your fist held at arm's length.

6. In the eastern dawn, between Venus and low Jupiter, Regulus is advancing upward for a meeting
with Mars.

7. In early dawn, watch Regulus passing slightly fainter Mars on the mornings of September 24th and
25th.
Friday, September 18
• As twilight fades, look low in the southwest for Saturn close to the waxing crescent Moon, as
shown here. To their left are Antares and other stars of upper Scorpius.
Saturday, September 19
• The crescent Moon at dusk now forms a triangle with Antares below it and Saturn to their right, as
shown here.
Sunday, September 20
• This is the time of year when, during the evening, the dim Little Dipper in the north "dumps water"
into the bowl of the Big Dipper way down below it. The Big Dipper dumps it back in the evenings of
spring.
Monday, September 21
• First-quarter Moon (exact at 4:59 a.m. Monday morning EDT). This evening the Moon shines above
the Teapot of Sagittarius. At this time of year, the Teapot is tipping increasingly far over, as if
pouring out the last of summer.

8. Tuesday, September 22
• The eclipsing binary star Algol should be at minimum brightness, magnitude 3.4 instead of its
usual 2.1, for a couple hours centered on 9:20 p.m. EDT according to Algol's recently updated
schedule.
Wednesday, September 23
• Binocular observers often scan the rich Milky Way of Cygnus now overhead. But do you know about
Omicron1
Cygni? It's a colorful double in the Swan's northwest wing. And a binocular challenge: it's
actually triple! See Gary Seronik's Binocular Highlight in the September Sky & Telescope, page 43.
• Autumn begins in the Northern Hemisphere, and spring in the Southern Hemisphere, at the
equinox: 4:21 a.m. Wednesday morning EDT (8:21 Sept. 23rd UT). This is when the Sun crosses the
equator heading south. Wherever you are, the Sun rises and sets almost exactly due west today.
Thursday, September 24
• Mars gleams less than 1° from Regulus in early dawn this morning and Friday morning. Look east.
They're 11° to the lower left of brilliant Venus, as shown here. Binoculars will help as dawn grows
bright.
And look for Jupiter 9° or 10° below or lower left of Mars and Regulus.
Friday, September 25
• Look far below the Moon this evening for 1st-magnitude Fomalhaut coming into view. It rises in
late twilight. How soon can you first spot it?
• Algol should be at minimum brightness for a couple hours centered on 6:09 p.m. EDT (going by
Algol's recently updated schedule). It takes several additional hours to rebrighten.
Saturday, September 26
• With the equinox past and fall under way, Deneb is taking over from Vega as the zenith star at
nightfall (for skywatchers at mid-northern latitudes). Look straight up at the end of twilight.
- See more at: http://www.skyandtelescope.com/observing/sky-at-a-glance/this-weeks-sky-at-a-
glance-september-18-26/?et_mid=784734&rid=250214192#sthash.VT0EoNGS.dpuf
This Week's Planet Roundup
Mercury is hidden in the glare of the Sun.
Venus is now at its greatest brilliancy (magnitude –4.8), the "Morning Star" high in the east during
dawn. It rises much earlier, around 3 or 4 a.m. depending on your location, a weird UFO of a thing.
In a telescope Venus is a thickening crescent, but shrinking in diameter week by week as it pulls
farther ahead of Earth around the Sun.
Mars, 400 times fainter at magnitude +1.8, glows 10° or 11° lower left of Venus in early dawn.
Regulus, slightly brighter at magnitude +1.4, shines closer below Mars early in the week, and moves
up closer to Mars each morning. Regulus passes just 0.8° to the right of Mars on the morning of
Friday the 25th.
Jupiter (magnitude –1.7) is even lower in the east during dawn. Look for it 9° below or lower left of
Regulus, as shown above.
Saturn (magnitude +0.6, at the Scorpius-Libra border) is moving lower and lower in the southwest at
dusk. Left of it by 11° twinkles orange Antares. Uranus (magnitude +5.7, in Pisces) and

9. Neptune (magnitude +7.8, in Aquarius) are well up in the east and southeast, respectively, by about
10 p.m. They're higher later. Finder charts for Uranus and Neptune. –
See more at: http://www.skyandtelescope.com/observing/sky-at-a-glance/this-weeks-sky-at-a-
glance-september-18-26/?et_mid=784734&rid=250214192#sthash.VT0EoNGS.dpuf
Get Ready for Upcoming Total
Lunar Eclipse
By: Alan MacRobert | September 14, 2015
On the night of September 27–28, the full Moon will plunge completely through Earth's shadow
for the last time until January 2018.
Watch the eclipse live! Our exclusive webcast begins Sunday night, September 27th, at 9:00 p.m.
Eastern Daylight Time (1:00 Universal Time on the 28th). Watch our streaming high-definition
coverage as the Moon glides into and out of Earth's deep umbral shadow, and hear commentary by
lunar experts!
This map shows locations from which this month's total lunar eclipse is visible. The timing favors
the Americas — especially the eastern parts — and western Europe and Africa.
S&T diagram
If your skies are clear after the Sun sets on Sunday, September 27th, be sure to head outside to see
the total lunar eclipse that happens that night. This will mark the end of a "tetrad" of four total lunar
eclipses spaced a half year apart that began back in early 2014. But, perhaps more importantly, it's
the last one visible anywhere until 2018.
Observers in the eastern half of North America can watch every stage of the eclipse, from beginning
to end of the partial phases (31
⁄3 hours in all) during convenient hours of late twilight or darkness
with the Moon mostly high in the sky. If you're in the Far West, the first partial stage of the eclipse is
already in progress when the Moon rises (due east) around the time of sunset. Those in Europe and
Africa see the eclipse on the local morning of the 28th.

10. During the upcoming total lunar eclipse, the Moon will take about 3.3 hours to cross Earth's umbra.
Sky & Telescope diagram
Unlike the lunar eclipse on April 4th, which might not even have been precisely total, this one will
carry the Moon through the umbra — the dark core of Earth's shadow — for 1 hour and 12 minutes.
Moreover, it's the biggest eclipsed Moon you'll ever see! That's because the closest lunar perigee of
2015 occurs just 59 minutes before mid-eclipse. The Moon (in Pisces) will appear 13% larger in
diameter than it did when eclipsed last April.
See the diagram above for key times during the eclipse. These occur simultaneously for everyone
who can see the Moon, but the event times vary depending on your time zone. So refer to the table
below for the times that are correct for you:
Key Times for Total Lunar Eclipse, Sept. 27–28, 2015
Eclipse event UT EDT CDT MDT PDT
Penumbra first seen? 00:40 8:40 p.m. 7:40 p.m. — —
Partial eclipse begins 01:07 9:07 p.m. 8:07 p.m. 7:07 p.m. —
Total eclipse begins 02:11 10:11 p.m. 9:11 p.m. 8:11 p.m. 7:11 p.m.
Mid-eclipse 02:48 10:48 p.m. 9:48 p.m. 8:48 p.m. 7:48 p.m.
Total eclipse ends 03:23 11:23 p.m. 10:23 p.m. 9:23 p.m. 8:23 p.m.
Partial eclipse ends 04:27 12:27 a.m. 11:27 p.m. 10:27 p.m. 9:27 p.m.

11. Penumbra last seen? 04:55 12:55 a.m. 11:55 p.m. 10:55 p.m. 9:55 p.m.
The events that happen to a shadowed Moon are more complex and interesting than many people
realize. For example, you can look for the first vestiges of shading on the Moon's southeastern side
(at lower left if seen from the U.S.) about 30 to 45 minutes before the lunar disk begins its dip into
the umbra. This duskiness intensifies as the Moon slides deeper into Earth's penumbra. An
astronaut standing on the Moon would see Earth covering only part of the Sun's face.
This month's total lunar eclipse, with its wide visibility, convenient evening schedule, and record
size, is going to get a lot of publicity. In fact, no matter where you are (or if your sky is cloudy), you
can watch the slow progression of this dramatic celestial event via Sky & Telescope's real-time
webcast.
- See more at: http://www.skyandtelescope.com/astronomy-news/observing-news/get-ready-for-
septembers-total-lunar-eclipse-
091420155/?et_mid=784734&rid=250214192#sthash.TEQSGCoc.dpuf