Journal of the Amateur Astronomers Association of New York

April 2015 Volume 64 Number 4; ISSN 0146-7662

Sizing Up Supernovae: How Dying Stars Give Life

By Richard Brounstein

“How are you feel-

ing? Do you have any

companions? How do

you interact with them?”

asks Dr. Alicia Soder-

berg. No, she’s not a

therapist; she’s an astron-

omer who heads Harvard

University’s Supernova

Forensics research group,

which poses these ques-

tions to dying stars.

Soderberg described her research into the private lives of su-

pernovae for the Frontiers Lecture at the American Museum

of Natural History on March 9.

Supernovae are enormous explosions that occur when

massive stars die. In their volatile death throes, they release

great energy and shock waves. They also have enough densi-

ty and pressure in their cores to create heavy elements like

iron, silver, and gold, which then spread into other parts of a

galaxy during the explosion. Low-mass stars can only pro-

duce lighter elements, like carbon. We are all made up of that

stardust. But, the iron in your blood, the jewelry you wear,

and the braces on your teeth could only come from superno-

vae. All these elements become the stuff of other stars, plan-

ets, and people – and everything that makes life possible.

Like compost, dead stars fertilize our galaxy.

We are able to observe supernovae in the days, months,

and years following their explosions. But, to truly understand

the life cycle of a supernova, we need to study its progenitor

– the star before it exploded. This is not easy, because we do

not know which stars are about to die. Distant stars about to

go supernova are even harder to predict, because they may

not be visible from Earth until they explode. Dying progeni-

tor stars are typically red supergiants with masses 20-30 times

that of the Sun. So far, scientists have discovered over 6,000

supernovae, but only 10 progenitors, so there is a great need

to expand our knowledge about the final days of massive

stars.

A supernova will occur about once a century in a galaxy

THIS MONTH: AAA Lecture on April 17 and AAA SolarFest on April 25!

AMNH FRONTIERS LECTURE

the size of the Milky Way. But across all the galaxies, it is

impossible to know which massive star will die next. Such

unpredictable events are often discovered by amateur astrono-

mers. With many more eyes on the sky and new telescope

technologies, three times as many supernovae are being dis-

covered now as were found a decade ago. Once a supernova

is reported, the event is announced globally throughout the

astronomical community, which quickly aims its telescopes at

the coordinates. It may take only 24 hours for a telescope to

focus on the event and classify the supernova.

Most studies of supernovae over the past few decades

have focused on visible light wavelengths, which produce the

strongest emissions during stellar explosions. But, Soder-

berg’s team observes supernovae at other wavelengths. For

instance, high energy observations have revealed that a small

percentage of supernovae give rise to gamma-ray bursts.

Soderberg’s discovery of SN 2008D while it was in the act of

exploding was made through X-ray observations. Sensitive

radio telescopes like the Expanded Very Large Array in New

Mexico and the Large Millimeter Array in Chile can observe

at longer wavelengths and may increase our ability to observe

progenitors.

But, Soderberg

doesn’t just observe

supernovae – she sets

them to music. For

each signal collected

across the light spec-

trum, her team as-

signs a different in-

strument. Radio

waves are drums. X-

rays play the harpsi-

chord. Each wave-

length joins the or-

chestra, taking up

instruments like the

violin or flute. The

resulting sonifications

don’t just make for

interesting melodies,

they provide a new

method for observing.

Listening to the music of the supernovae, a blind member of

Soderberg’s team has been able to identify elements that oth-

ers were unable to distinguish by analyzing the data visually.

(AMNH Frontiers Lecture, cont’d on page 4)

Harvard University

Dr. Alicia Margarita Soderberg leads Harvard’s Supernova Forensics team.

NASA/JPL-Caltech/ UCLA/MPS/DLR/IDA

NASA’s Dawn became the first space-craft to orbit a dwarf planet, arriving at Ceres in the Asteroid Belt on Mar 6.

ALMA

At just 168,000 light-years away and visible to the naked eye, SN1987A was the closest supernova to be observed

from Earth since Kepler’s Supernova of 1604. The event gave modern astrono-

mers the first chance to see a core-collapse supernova up close.

2

April’s Evening Planets: Mars is can be seen in the

west until 8 PM this month. Venus is visible in Taurus the

Bull until 10 PM, setting later each night toward 11PM at the

end of April. Bright Jupiter is in Cancer the Crab all night.

For about an hour after sunset, Mercury is between Taurus

and Aries the Ram for the last ten days of April.

April’s Evening Stars: Spot Capella in Auriga the

Charioteer, and Spica in Virgo the Virgin, Procyon in Canis

Minor the Small Dog, Arcturus in Bootes the Herdsman, and

bright Castor and Pollux in Gemini the Twins. Also find the

stars of constellations Cassiopeia, Perseus, Cepheus, Draco,

Virgo, Hercules, Leo, Cancer, Corona Borealis, and the two

Dippers during the month.

April’s Morning Planets: Jupiter will linger in Cancer

the Crab until 4 AM, setting earlier every morning toward 2

AM by the end of the month. Saturn will rise in Scorpius the

Scorpion at midnight, and earlier toward 10 PM at the end of

April, staying up until sunrise. Neptune will be in Aquarius

the Water Bearer shortly before sunrise. Dwarf planet Pluto

will be in Sagittarius the Archer by 3 AM, rising earlier each

night.

April’s Morning Stars: See the Summer Triangle of

Vega in Lyra the Harp, Deneb in Cygnus the Swan, and Al-

tair in Aquila the Eagle around 2 AM, rising earlier each

night during April. Look for reddish Antares in Scorpius the

Scorpion, Arcturus in Bootes the Herdsman, and Spica in

Virgo the Virgin, along with the stars of constellations Lyra,

Hercules, Libra, Corona Borealis, Scorpius, Sagittarius, Cas-

siopeia, Cepheus, Draco, and the two Dippers.

Apr 1 Moon at apogee (252,293 mi from Earth)

Apr 4 Full Moon at 8:05 AM

Total lunar eclipse, partially visible in NY

Apr 8 Saturn 3° south of the Moon (morning)

Apr 11 Last Quarter Moon at 11:45 PM

Apr 16 Moon at perigee (224,325 mi from Earth)

Apr 18 New Moon at 2:55 PM

Apr 22 Sirius, Betelgeuse, the Moon, and Capella

line up (after sunset)

Apr 23 Lyrid meteor shower peaks (dawn)

Apr 25 First Quarter Moon at 7:55 PM

Apr 28 Moon at apogee (251,720 mi from Earth)

Times given in EDT.

WHAT’S UP IN THE SKY

April 2015

The First “Blood Moon” Eclipse of 2015

In the early morning hours of April 4, the Moon will undergo

a total lunar eclipse, allowing Earth’s natural satellite to shed

its silver-white brightness and become a haunting reddish

disk.

Is it really going to look red?

During a total lunar eclipse, Earth is positioned directly be-

tween the Sun and a full Moon, blocking the Sun’s light from

the Moon. At the maximum point of the eclipse, or totality,

light disseminated by the Earth’s sunrises and sunsets falls

on the Moon, giving the celestial body a coppery-red look.

In general, the Moon appears dark at the beginning and end

of the eclipse, and reddish at the mid-point. The April 4 total

lunar eclipse will be the shortest of the 21st century; totality

will last for only about 5 minutes.

Is it visible from New York?

Partially. The beginning of the

lunar eclipse can be seen from

New York City at 5:03 AM

with the start of the penumbral

phase, when only the diffuse

outer shadow of Earth falls on

the Moon. It first enters into

Earth’s darker umbral shadow

at 6:15 AM, but the Moon sets

soon after at about 6:30 AM, so

New Yorkers will miss the

“Blood Moon” maximum

at 8:00 AM. The umbral phase lasts about three-and-a half

hours. The entire eclipse process takes about six hours to

complete, ending around 11:00 AM.

Who else can see the total eclipse?

The full eclipse will

be over the Pacific

Ocean and can be

viewed in eastern

Australia, New Zea-

land, eastern Japan,

and in Alaska and

Hawaii. Most of the

U.S., Canada, and South America will be able to view part of

the eclipse event until sunrise. East Asia and Central Asia

will be able to watch part of it until sunset.

What do I need to see the eclipse?

The lunar eclipse can be viewed by the naked eye, and all

you really need are clear skies. Even with city lights close

by, the Moon will still be visible. However, it will be ap-

proaching the horizon, so it is recommended that you go to a

high point for better viewing.

When is the next lunar eclipse?

The next total lunar eclipse in 2015 will take place

on September 28. Source: timeanddate.com.

Follow veteran sky watcher Tony Faddoul each month, as he points our minds and our scopes toward the night sky.

AAA Observers’ Guide

By Tony Faddoul

April “Skylights”

3

April 2015

Seen in Space Cosmic Showers Don’t Bring Galaxy Flowers

NASA’s Chandra X-ray Observatory has found that

a cycle of cosmic precipitation allows supermassive black

holes to regulate how galaxies grow. In February,

NASA’s NuSTAR and ESA’s XMM-Newton X-ray tele-

scopes discovered that jets of radiation, powered by super-

massive black holes at galaxy centers, blow out in all direc-

tions, heating gas and preventing stars from forming. But

what gets those jets going? Data from Chandra now reveals

that cool gas clouds rain down on the black hole, producing

the jets. The catch is this: the hot jets themselves cause the

cool showers. In a feedback

loop, gas heated by the jets

loses energy quickly and

creates cool clouds – some

of which form stars, while

others rain on the black hole,

producing the jets that heat

the gas. “Without these

black holes and their jets,

the central galaxies of gal-

axy clusters would have

many more stars than they

do today,” said co-author

Michael McDonald of MIT.

And so the cycle goes, but

for how long? Studying

over 200 galaxy clusters, Chandra scientists estimate that the

precipitation cycle has regulated galaxy growth for the last 7

billion years or more. But, they also found that some central

galaxies have “dried up.” Collisions with other clusters may

have made it too hot for gas to cool into cosmic clouds. In

others, the drought may be “temporary” because of a particu-

larly strong burst of black hole jets; rain should resume in a

few hundred million years. AMW Sources: chandra.si.edu; nasa.gov.

NASA/CXC/DSS/Magellan

Composite image of galaxy clus-ter Abell 2597. A cycle of cosmic precipitation at its central galaxy’s

supermassive black hole regu-lates star formation.

Mad for Mars Oceans Away! Martian Water Found to be Lost

4.3 billion years ago,

Mars had enough water to

cover its surface in a layer of

liquid 450 feet deep, NASA

scientists reported in March.

Using ground telescopes at the

W.M. Keck Observatory,

NASA Infrared Telescope Fa-

cility, and the European South-

ern Observatory’s Very Large

Telescope, they determined

how much water Mars once

had and how it lost that water

over time, comparing the

planet’s current atmospheric water with water from a 4.5 bil-

lion-year-old Martian meteorite. Specifically, they looked at

ratios of H2O to HDO in the water. D represents deuterium,

or “heavy hydrogen,” a naturally occurring isotope of the at-

om. While hydrogen becomes lost to space over time, deuter-

ium stays trapped in the water cycle. Infrared mapping of

global H2O/HDO ratios found that Mars’ polar ice caps, the

largest remaining water reservoir, are highly enriched with

deuterium. The volume of the caps was once 6.5 times great-

er than it is now. As Mars lost its atmosphere, it lost the pres-

sure and heat needed to keep water liquid. 87% of Mars’ wa-

ter has been lost to space. Researchers believe that ancient

Martian water once formed a one-mile-deep ocean that cov-

ered the low-lying Northern Plains, occupying 19% of the

Red Planet’s surface with a volume of 5 million cubic miles.

That’s more water than is contained in Earth’s Arctic Ocean.

“With Mars losing that much water, the planet was very likely

wet for a longer period of time than was previously thought,

suggesting it might have been habitable for longer,” said Mi-

chael Mumma, an author on the study. AMW Source: nasa.gov.

NASA/GSFC

Mars once had an ocean over almost half of its northern hem-

isphere, lost to space as its atmosphere disappeared.

Head’s Up! Raging ‘Roids in Near-Earth Orbit

To date, NASA has found more than 12,000 near-Earth objects, asteroids and small

bodies that orbit the Sun in proximity to our planet. So far , none of those found that are

more than half-a-mile in size will impact Earth within the next 100 years. But as of last year,

NASA counted at least 1,472 smaller asteroids that will pass near Earth and threaten impact.

Since launching its Asteroid Initiative in 2012, NASA has increased detection of near-Earth

asteroids by 65%. It has also called on the public to join in the hunt for NEOs through its As-

teroid Grand Challenge. In partnership with Planetary Resources, Inc., NASA released in

March a software application that came out of that challenge. Asteroid Data Hunter uses a con-

test-winning algorithm to analyze and narrow down tons of images for amateur astronomers to

make new NEO discoveries. It can be downloaded at http://www.topcoder.com/asteroids/.

Also in March, data from NASA's Near-Earth Object Wide-field Survey Explorer (NEOWISE) space telescope was

made available online to the public at http://wise2.ipac.caltech.edu/docs/release/neowise/. Millions of images and billions

of measurements of asteroids, stars, galaxies, and quasars were taken between December 2013 and 2014. NEOWISE collected

data on over 10,000 items, revealing 129 new Solar System objects, including 39 previously unknown near-Earth objects. 8 of

these have been classified as PHAs: potentially hazardous asteroids. "And we're far from finished," said Amy Mainzer, NE-

OWISE’s principal investigator. “We've already added another 21 new discoveries including six new near-Earth objects." Able to

see an object’s heat signature in infrared light, NEOWISE helps determine size and composition. It also looks toward dawn and

twilight skies – perpendicular to the line between Earth and the sun. So, NEOWISE can spot objects approaching from the direc-

tion of the sun, unlike ground-based telescopes that can only view the night sky. AMW Sources: nasa.gov; neowise.ipac.caltech.edu..

NASA/JPL-CalTech

The NEOWISE space telescope has revealed 8 new potentially

hazardous near-Earth asteroids.

4

April 2015

But, we don’t need to look up to see the effects of star

explosions, supernovae remnants are right under our feet.

During Earth’s 4.5 billion years, tens of thousands of stellar

explosions have occurred in the Milky Way, many within a

few light years of our Solar System. Matter that was ejected

from supernova explosions over the last million years and

deposited into the Earth’s crust and oceans can be gathered

and studied today. These remnants contain 244Pu, an isotope

of plutonium that is created during supernovae. Some 244Pu

existed in our nebula at the time of Earth’s formation, but

with a half-life of 80 million years (that’s 57 half-lives during

Earth’s time), very little of it should remain on our planet.

Yet, there seems to be more than there should be. The most

logical explanation for the excess 244Pu is supernovae. Soder-

berg and her team ex-

amine the rocks off of

Cape Cod in Massachu-

setts for 244Pu and other

elements produced by

supernovae. By dating

these elements, she can

determine if and when a

supernova has occurred

in our galaxy.

So if we were to

play therapist, what

would a psychoanalysis

of supermassive stars

reveal? They have a death wish. But it’s a good thing they

do – when it comes to understanding our universe and our

place in it, we’re glad they go out with a bang.

Sources: scholar.harvard.edu; wiki..

AMNH Frontiers Lecture (cont’d from Page 1)

Iron in our blood, silver and gold in our jewelry, and metal used in our dental

work all come from supernovae.

5

Explore more night sky photography at

www.stanhonda.com

Mooning Over a Planetary Conjunction

By Stan Honda

In February, astronomy websites and magazines geared

up for a planetary conjunction: Venus and Mars were ap-

proaching each other in the sky, and on Feb 21 they would be

less than 1° apart; the Moon would hover 10° above. But as a

photographer, I found the star charts for the previous night to

be far more enticing – the planets would be joined in the sky

by a 2-day-old crescent Moon, all within 2° of each other.

The Feb 20 alignment would be a great opportunity for

almost any type of camera. Planetary conjunctions are easily

photographed in urban settings. Jupiter and the inner planets

are bright enough to be visible from New York City, where

they can take on a dreamy appearance floating above Manhat-

tan’s skyline. And, you don’t need fancy equipment to cap-

ture interesting images – especially in this case, when the thin

Moon’s light won’t overpower the planets.

That evening, I headed from my apartment on the east

side of Manhattan to Central Park, in search of a western

view. The sky was clear the whole day and night on Feb 20,

but it was very cold. It was 17°F when I set out, so I put on

many layers and a pair of hand warmers.

I first shot a few pictures through some trees along the

Park’s perimeter road, but big piles of snow and glaring

streetlamps prevented me from getting a good angle of the

trio, so I ascended a flight of stairs to the running track

around the Reservoir. From the track, there is a clear view

across the water to the west side of Manhattan. The buildings

aren’t enormously tall there, so you can see down as low as

5° above the horizon. The track was covered by ice, and I

didn’t expect to see the usual joggers. But, there they were.

Two hardy souls ran by during the hour I spent there.

On the track, I set up my tripod and camera/lens combo.

I used a 70-200mm zoom lens set at 200mm, a relatively

modest telephoto setting. On a full-frame camera, that focal

length covers an area of 7° x 10°; the 2° separation of the

Moon and planets would fit well within the frame. This size

also allowed me to include other objects, like buildings and

trees, adding some perspective to the image. Around 7 PM,

April 2015

Venus, Mars, and the Moon had set far enough in the west for

me to frame them with some buildings for a close-in shot.

There is one advantage to photographing the night sky

in a bright city like New York – the exposure for the skyline

is the same as for the planets and Moon. Of course, I would

trade that for a better view of the stars.

The Sony a7S that I used has a couple of great features

to make night sky photography even easier. A pullout screen

gives a live view to compose a shot; this will save you from

having to crane your neck to look in the viewfinder. It also

has extremely high ISO settings: up to 406,000 ISO. I ex-

perimented, starting at 3,200 ISO and going as high as 12,800

ISO. The higher setting allowed me to shoot at ¼-sec shutter

speed instead of the usual 1-sec or more.

To capture the celestial bodies with a particular group of

tall buildings, I walked north on the track – not an easy task

on the ice. As they began to set, the Moon and planets

seemed to pick up speed, so I quickly set up my tripod. I took

a few pictures with the zoom lens at 200mm and also grabbed

some wider shots of the skyline. The Moon then dipped be-

hind a building, with just the tips of its crescent poking out

like horns. Then it was gone. I packed up and headed home

with frozen hands – my sacrifice for winter photography.

Editing back in my warm apartment, I selected a photo

where the three objects seemed balanced between two build-

ings. I cropped in tightly to focus on the formation, which

makes the relative size of the Moon larger and draws attention

to the conjunction. A wider shot, however, gives a better

sense of location, and the Manhattan skyline is unmistakable.

There are several more opportunities to photograph or

observe planetary conjunctions in 2015. This summer, Venus

and Jupiter will set together during early and mid-July, while

Jupiter pairs with Mercury in early August. In the fall, Ve-

nus, Mars, and Jupiter will put on a show as they pass by each

other around Oct 26.

FOCUS ON THE UNIVERSE

Stan Honda is a professional photographer. Formerly with Agence

France-Presse, Stan covered the Space Shuttle program. In his

“Focus on the Universe” column, he shares his night sky images and

explores his passions for astronomy and photography.

Stan Honda

Sony a7S camera, Nikon 70-200mm f4 lens at 70mm. Exposure: ½ sec, f4, ISO 3200.

Stan Honda

Sony a7S camera, Nikon 70-200mm f4 lens at 200mm. Exposure: ¼ sec, f4, ISO 12,800.

Submit your photography questions to stanhonda@gmail.com.

6

April 2015

Telescope of the Month India’s Vainu Bappu Telescope Named for the father of modern Indian astronomy, the Vainu Bappu Telescope

is located at the Vainu Bappu Observatory in Kavalur, India, 112 miles outside Bangalore. Oper-

ated by the Indian Institute of Astrophysics, the 2.34m VBT is the largest optical telescope in

Asia. Ideal for deep sky observations, it has an f/3.25 prime focus and an f/13 Cassegrain focus.

Its equatorially mounted horseshoe yoke is especially suited for low latitudes. The telescope was

the brainchild of Bappu, who died four years before its completion in 1986. Bappu co-discovered

the Wilson-Bappu effect, showing a correlation between the width of certain spectral emission

lines in the cores of cool stars and their absolute magnitude. The wider the lines, the brighter the

star. Comparing absolute magnitude and a star’s apparent magnitude, astronomers can determine stellar distance. The Kavalur

site was established for better night sky viewing in the 1960s by Bappu, then director of the Kodaikanal Observatory, a solar ob-

servatory dating back to colonial rule under the U.K. In addition to the VBT, Kavalur hosts several smaller reflectors and a 1m

Zeiss telescope, which discovered in 1972 an atmosphere around Jupiter’s moon Ganymede. It also confirmed the 1977 discovery

of rings around Uranus. In 1988, Kavalur’s 18” Schmidt telescope discovered minor planet 4130 Ramanujan in the Asteroid Belt.

A new, double-horseshoe 1.3 m telescope at Kavalur was recently installed in a special, temperature-regulating dome. AMW Sources: astroproject.in; iiap.res.in; wiki.

Prateek Karandikar

The 2.3m Vainu Bappu is the largest optical telescope in Asia.

Hubble Hubbub Oceans Abound! Ganymede’s Got Water

In March, NASA announced that the Hubble Space

Telescope has found evidence of an underground ocean

on Jupiter’s icy moon Ganymede. The largest moon in the

Solar System, Ganymede is the only one to possess a magnet-

ic field. As on Earth, Ganymede’s magnetic field produces

aurorae at north and south poles. Aurora lights are caused

when charged particles from

solar wind come into contact

with elements in the atmos-

phere. The particles travel

along the magnetic field

lines, which dip toward the

surface at the poles. Gany-

mede’s close orbit of Jupiter

is within the giant planet’s

own magnetic field, which

influences the moon’s auro-

rae. As Jupiter’s field chang-

es, Ganymede’s aurorae

“rock” back and forth. Mon-

itoring the aurorae in ultravi-

olet light, which can only be

done in space with a tele-

scope like Hubble, scientists

found they don’t rock as much as they should. “Magnetic

friction” from a secondary magnetic field in a saltwater ocean

is countering the influence of Jupiter’s field. The field in

Ganymede’s underground ocean puts up a good fight, reduc-

ing the rocking of the aurorae by as much as 4 degrees. Sci-

entists calculate that Ganymede’s subterranean ocean must be

60 miles deep beneath a 95-mile layer of ice crust, containing

more water than all of Earth’s oceans combined. “In its 25

years in orbit, Hubble has made many scientific discoveries

in our own solar system. A deep ocean under the icy crust of

Ganymede opens up further exciting possibilities for life be-

yond Earth.” said John Grunsfeld of NASA's Science Mission

Directorate. AMW Sources: .nasa.gov.

NASA/ESA

The Hubble Space Telescope monitored the aurorae of the icy

Jovian moon Ganymede and researchers found their motions indicate there is an enormous

underground ocean lies beneath the large moon’s frozen crust.

Celestial Selection of the Month The Southern Pinwheel

Spiral galaxy M83 is a busy place. Six br ight super -

nova explosions have been recorded over time in the galaxy,

which is barred like our own Milky Way, and its center is a

hub of stellar birth. Two hubs, in fact. The European South-

ern Observatory’s Very Large Telescope in Chile has ob-

served a double circumnuclear ring at its center, so M83 has

two galactic nuclei. In 2008, NASA’s Galaxy Evolution Ex-

plorer (GALEX) also unexpectedly found a large number of

newborn stars in the galaxy’s outer reaches.

Known as the Southern Pinwheel, the M83 galaxy is

very bright and very close. At only 15 million light-years

away in the constellation Hydra, it can be seen easily with

binoculars. It was first discovered in 1752 at the Cape of

Good Hope in South Africa by Abbot Nicolas Louis de La-

caille. The French astronomer famously traveled there to

construct an observatory where he could measure the lunar

and solar parallaxes as well as planetary distances. Observing

every night for over a year, he also catalogued nearly 10,000

stars of the

southern sky

and 42 celes-

tial objects,

including

M83, which

he had be-

lieved was a

gas cloud.

Back home at

work in his

private obser-

vatory at

Mazarin Col-

lege in Paris,

he calculated comet orbits. He is also responsible for naming

Halley’s Comet. After his death in 1762 at age 48, his south-

ern catalogue Coelum Australe Stelliferum was published.

AMW Sources: wiki; apod.nasa.gov.

NASA/ESA/Hubble Heritage Team/W.P. Blair, et al.

At the very active center of the spiral galaxy Southern Pinwheel (M83) in the Hydra constella-

tion there are two separate nuclei.

7

April 2015

CALL FOR WRITERS

Do you enjoy reading the Eyepiece?

How would you like to see your name in print?

The Amateur Astronomers Association of New York’s journal Eyepiece is looking for dedicated writers to contribute articles covering lectures, seminars, and

observing events around town, as well as current topics in astronomy and astrophysics.

Interested? Please submit a short writing sample to Amy Wagner at editor@aaa.org.

Probing the Universe Oceans Alive? Hydrothermals on Enceladus

In March, two teams of Cassini spacecraft scientists

announced evidence of hydrothermal vents at the bottom

of the ocean on Saturn’s moon Enceladus, where life

forms could exist. On Ear th, seawater interacts with the

rocky crust beneath, creating vents that heat the surrounding

water and enrich it with minerals. Despite harsh conditions,

more than 300 species of tubeworms, fish, crabs, shrimp,

clams, anemones, and chemosynthetic bacteria thrive in the

extreme heat, pressure, and darkness around the vents. In

2005, Cassini first discov-

ered jets of water ice and

vapor, salts, and organics

pluming out of fractures in

Enceladus’s icy surface, and

last year scientists deter-

mined that a 6-mile-deep

ocean lies under a 25-mile-

layer of ice. Now, a study

has shown that microscopic

grains of silica rock spewed

from Enceladus’s jets were

produced by hydrothermal

activity in that subsurface

ocean. On Earth, such

grains are commonly

formed when mineral-rich

hot vent water comes into

contact with cooler ocean

water as it rises up. "We methodically searched for alternate

explanations for the nanosilica grains, but every new result

pointed to a single, most likely origin," said Cassini scientist

Frank Postberg. Another study explained that hydrothermal

activity is responsible for an abundance of methane gas in

Enceladus’s plume. Under its high pressures, Enceladus’s

ocean should trap most methane in icy materials called clath-

rates. While it’s possible the clathrates released their me-

thane as they erupted through the plume, it is more likely that

hydrothermal vents produce methane at a rate faster than can

be converted into clathrates. AMW Sources: saturn.jpl.nasa.gov; onr.navy.mil.

NASA/CXC/DSS/Magellan

In 2005, Cassini imaged a plume of water vapor erupting from

Saturn’s icy moon Enceladus. It contains silica grains and methane from hydrothermal activity at the bottom of a subsurface ocean.

8

April 2015

Eyepiece Staff April Issue

Editor in Chief: Amy M. Wagner Copy Editor: Richard Brounstein

Contributing Writers: Richard Brounstein,

Tony Faddoul, Stan Honda, and Amy Wagner

Eyepiece Logo and Graphic Design: Rori Baldari

Administrative Support: Joe Delfausse

Printing by McVicker & Higginbotham

Hello AAA Members!

Spring is finally here – although we have had

very little spring weather yet! With the approach-

ing warmer weather comes more outdoor observ-

ing. Some of our observing locations actually

started up in March, and most will begin this

month. Our new and improved AAA website at

www.aaa.org will continue to provide updates to

the 2015 calendar as we confirm dates.

Meanwhile, don’t miss the next installment of

the AAA Lecture Series at the American Museum

of Natural History. Our speaker will be Robert

Fisher from the University of Massachusetts, pre-

senting "Exploding Stars and the Accelerating

Cosmos" on Friday, April 17. This season's full

schedule is available at www.aaa.org/lectures.

Also, I hope to see you at AAA’s Annual

Spring Starfest at Woodlawn Cemetery on Sat-

urday, May 2. As usual, there will be nighttime

observing, raffles, and prizes. We will start early

with solar observing in the afternoon. Be sure to

check out the AAA website for details.

Marcelo Cabrera

President, AAA

president@aaa.org

SAT, Apr 4

@ 8 pm – 11 pm Next: Every Friday & Saturday Night

AAA Observing at Lincoln Center Plaza – Manhattan, PTC

@ 9 pm – 11 pm Next: May 2

AAA Observing at Brooklyn Museum Plaza – Brooklyn, PTC

TUES, Apr 7

@ 8 pm – 11 pm Next: Every Tuesday Night

AAA Observing at the High Line – Manhattan, PTC

FRI, Apr 10 @ 8 pm

Columbia University Stargazing & Lecture at Pupin Hall, P

“Galactic Synthesizers” with Adrian Price-Whelan. (Observing 8:30 pm, C)

MON, Apr 13 @ 7:30 pm

AMNH Frontiers Lecture at the Hayden Planetarium, P

“How to Take a Picture of a Black Hole: Building the Event Horizon

Telescope” with Shep Doeleman at the American Museum of Natural

History. Explore the evidence for black holes and learn about an Earth-

sized telescope to image our Milky Way’s black hole. (Enter 81st St)

FRI, Apr 17 @ 6:15 pm Next: May 1

AAA Lecture at AMNH, M

“Exploding Stars and the Accelerating Cosmos” with Robert Fisher of

UMASS in the Kaufmann Theater. (Enter 77th St)

SAT & SUN, Apr 18-19

2015 North-East Astronomy Forum in Suffern, NY, PT

Rockland Astronomy Club hosts the world’s largest astronomy expo

with vendors, workshops, solar observing, raffles, and more at SUNY

Rockland Community College. Speakers will include NASA/JPL’s

Marc Rayman, Chief Engineer for the Dawn Mission, and Bill Ger-

stenmaier, Director of NASA’s Human Space Flight Program.

(For tickets visit http://rocklandastronomy.com/neaf.html.)

TUES, Apr 21 @ 6:30 pm

AMNH Astronomy Live at the Hayden Planetarium, P

“How Big is the Universe?” It hasn’t been easy calculating the scale

of the universe or determining Earth’s position in it. Explore the history

of human perception of the universe with Brian Levine. (Enter 81st St)

FRI, Apr 24

@ 8 pm – 11 pm Next: May 22

AAA Observing at Carl Schurz Park – Manhattan, PTC

@ 8 pm – 10 pm Next: May 23

AAA Observing at Floyd Bennett Field – Brooklyn, PTC

@ 8 pm – 10 pm Next: May 23

AAA Observing at Metropolitan Oval Parkchester – Bronx, PTC

@ 8 pm (Observing @ 8:30 pm, C)

Columbia University Stargazing & Lecture at Pupin Hall, P

“Dark Matter of Ghost Galaxies” with Jana Grcevich.

SAT, Apr 25

@ 10 am – 1 pm

AAA SolarFest at Edgar Allen Poe Park in the Bronx, PTC

Celebrate the 90th anniversary of the 1925 Solar Eclipse with AAA and Joe

Rao. Join for solar observing and a talk with Rao, meteorologist of Hudson

Valley News 12 and associate at the Hayden Planetarium, who will discuss

the history of the famous eclipse and his own adventures in solar observing.

For details visit www.aaa.org/observing/solarfest.)

@ 8:30 pm – 11 pm Next: May 23

AAA Observing at Great Kills – Staten Island, PTC

C: Cancelled if cloudy; M: Members only; P: Public event; T: Bring telescopes, binoculars.

For location & cancellation information visit www.aaa.org.

AAA Events on the Horizon A Message from the AAA President

The Amateur Astronomers’ Association of New York Info, Events, and Observing: president@aaa.org or 212-535-2922

Membership: members@aaa.org Eyepiece: editor@aaa.org

Visit us online at www.aaa.org.