FRIENDS OF THE PLANETARIUM NEWSLETTER – MARCH 2014
Using a telescope located near the South Pole,
scientists recently announced the discovery of
primordial gravitational waves. Pardon the
pun but the announcement sent ripples
through the astrophysics and cosmology
communities. If the results are verified, they
provide the evidence necessary to confirm the
theory of inflation, one of the key components
of the Big Bang theory. The telescope used to
detect the gravitational waves is called
BICEP2, short for Background Imaging of
Cosmic Extragalactic Polarization. The BICEP2
scope has an aperture of less than 30
centimeters, but it doesn’t need to be big.
Cooled to 4 degrees Kelvin, it gazes at a 20 degree patch of sky 24/7, detecting faint microwaves and,
crucially, how they’re polarized.
Our universe burst into existence in an event known as the Big Bang 13.8 billion years ago. Moments
later, space itself ripped apart, expanding exponentially in an episode known as inflation. Telltale signs
of this early chapter in our universe's history are imprinted in the skies, in a relic glow called the cosmic
microwave background. Recently, this basic theory of the universe was again confirmed by the Planck
satellite. Researchers however still weren’t satisfied. They had long sought more direct evidence for
inflation in the form of gravitational waves, which squeeze and stretch space. The gravitational waves
produced a characteristic swirly pattern in polarized light, called "B-mode" polarization. Light can
become polarized by scattering off surfaces,
such as a car or pond. Polarized sunglasses
reject polarized light to reduce glare. In the
case of the cosmic microwave background,
light scattered off particles called electrons
to become slightly polarized. As a result of
experiments conducted since 2006, the
team has been able to produce compelling
evidence for the B-mode signal, and with it,
the strongest support yet for cosmic
inflation. Using 3 years of data, the BICEP2
team meticulously analyzed their
polarization measurements. They also compared their data with observations from BICEP1 and from
the team’s new Keck Array, which is basically like five BICEP2s in one. It was this ability to combine
three data sets that ultimately allowed the team to make the discovery. The measurement also suggests
that inflation might have had something to do with the unification of three of the four fundamental
forces of nature: the strong, weak, and electromagnetic. The energy level implied by the BICEP2 data, 2
× 1016 GeV, or roughly a trillion times the energy of the Large Hadron Collider, matches the energy of
grand unified theories, or GUTs. That’s an idea theorists have toyed with since the 1970s, but the
BICEP2 result is the missing link they’ve sought for decades. Scientists are piecing together an
increasingly accurate picture of the universe and its history, but there is still much left to be learned.
The first of two lunar eclipses for the year takes place on the evening of April 15. The penumbral stage
of the eclipse starts a few minutes before 5 pm NZST, up to an hour before moonrise in New Zealand.
During the penumbral stage there is little to see as the moon is only in partial shadow. The Earth’s dark
Umbra starts moving onto the moon just before 6 pm. For most of New Zealand, except the extreme
south, this is just after moonrise, so the moon will be very low. Over the next hour the Earth’s dark
shadow will move over the face of the moon until it is totally in shadow soon after 7 pm. By then the
moon will be a little higher, but still rather low to the east. Mid eclipse is just after 7.45 pm NZST and
totality ends just before 8.25. Under ideal conditions the moon can turn a blood red colour around the
time of mid-eclipse. The Earth’s dark shadow finally leaves the moon just after 9.30 pm.
The moon has been in the news recently for a different reason. The high-speed impact of a wayward
space rock on the surface of the moon last
year triggered the brightest lunar
explosion ever seen, scientists say. Video
footage of the record-breaking meteorite
strike on the moon, which occurred on
Sept. 11, 2013 and was unveiled on Feb.
24, shows a long flash that was almost as
bright as the star Murzim, the front paw
of Canis Major. That means the bouldersized meteorite's lunar crash could have
been visible to anyone on Earth who
happened to be staring up at the moon at
8:07 p.m. GMT, weather permitting. The
space rock hit at a staggering speed of
61,000 km/h, gouging out a new crater
roughly 40 meters wide in an ancient
lava-filled lunar basin known as Mare
Nubium. Scientists think the boulder
behind the crash was about 400 kg and measured between 0.6 and 1.4 meters in diameter. The energy
released by the September 2013 impact was comparable to an explosion of roughly 15 tons of TNT. It
was at least three times more powerful than the largest previously observed event.
NASA’s Kepler space telescope is the world’s most successful planet hunter and is often called one of
NASA’s greatest successes ever. For nearly 4 years, Kepler continuously monitored 150,000 stars
searching for tiny dips in their light when the silhouettes of planets crossed in front of them. Among
Kepler’s finds are some of the most extreme and uncanny worlds yet known. It has caught planets that
nearly scrape their host star’s surface, others that orbit a pair of suns, and multi-planet systems that are
crammed into a space smaller than the orbit of Mercury. Last month the Kepler science team broke
another record by adding 715 newly confirmed exoplanets to its tally, nearly doubling the number of
planets known to humanity. These newly verified worlds are all in multi-planet systems, dubbed
“multis”, which is how they were confirmed. Most are relatively small; 95% rank as Neptunes, miniNeptunes, super-Earths, and almost-Earths. The total number of known Earth-sized planets increased
by 400%, super-Earths by 600%, and Neptunes by 200%. Excitingly, 4 of the new planets are less than
2.5 times the diameter of Earth and orbit in their star’s habitable zones. If four sounds like a
depressingly skimpy number compared to 715, that’s because Kepler mainly finds broiling furnace
worlds close to their suns. These simply have the greatest chance of causing transits from Earth’s
arbitrary viewpoint. Similarly large numbers likely orbit in the more clement zones a little farther out.
Kepler’s results have reinforced the finding that planetary systems come in a huge variety, some
drastically different from our own, and even called into question our understanding of multi-planet
systems. Nature has proven able to cram a surprising number of planets near each other in orbits
smaller than Venus’s or even Mercury’s. The record-holder in the newly announced tally is Kepler 90: a
Sun-like star with at least 7 transiting planets all circling the star within the Earth's orbit.
Memberships subs are now due for 2014 (unless you joined in the past six months). A new membership
form is enclosed (printed copies) and available on our website, along with Internet deposit details.