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Monthly Archives: December 2013

The European Space Agency’s billion-star surveyor, Gaia was launched into space on Thursday December 19, 2013, where it will embark on its mission to create a highly accurate 3D map of our galaxy. (See pp. 285, 290.)


Credit: ESA

By repeatedly observing a billion stars, with its billion-pixel video camera, the Gaia mission will allow astronomers to determine the origin and evolution of our galaxy whilst also testing gravity, mapping our inner Solar System, and uncovering tens of thousands of previously unseen objects, including asteroids in our Solar System, planets around nearby stars, and supernovae in other galaxies.

Gaia will map the stars from an orbit around the Sun, near a location some 1.5 million km beyond Earth’s orbit known as the L2 Lagrangian point. The spacecraft will spin slowly, sweeping its two telescopes across the entire sky and focusing their light simultaneously onto a single digital camera, the largest ever flown in space. The ‘eye’ of Gaia’s camera has the most sensitive set of light detectors ever assembled for a space mission.

Once Gaia starts routine operations, in late Spring 2014, astronomers will have the challenge of dealing with a flood of data. Even after being compressed by software, the data produced by the five-year mission will fill over 30,000 CD-ROMs!

The first Gaia science is expected to be discoveries of new sources – supernovae, extreme variable stars, and blazars.

Links: University of Leicester press release; ESA launch campaign blog and press release; ESA lift-off movie.

A new annotated guide to written, web, and audio-visual resources for teaching and learning about planets orbiting other stars has been released.  Materials in the guide to this rapidly-changing branch of astronomy include video and audio files of lectures and interviews with leading scientists in the field, phone and tablet apps, a citizen-science web site, popular-level books and articles, and more.

Published by the NASA Astrophysics Education and Outreach Forum and the Astronomical Society of the Pacific, the guide can also be found as a PDF file. Find out more here:

From the International Astronomical Union’s Newsletter of the Commission 46 on the Teaching of Astronomy (coauthor Jay M. Pasachoff was president of the Commission):
Anja C. Andersen (Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen) notes the following resource that may be of interest to astronomy educators. “Studynova is a project by Canadian Mitch Campbell. There, students can find hundreds of videos on the subjects of mathematics and physics. There are three topics in particular that are of interest to astronomy students. First, under ‘physics’, is a set of 48 videos on astrophysics. These are relevant for high school and introductory university students, and are an overview of common astrophysics topics (including stellar properties, HR diagrams, calculating distances, cosmology, etc). Second, also under ‘physics’, is a set of 23 videos called ‘Astrophysics extra’. These feature additional material for high school and introductory university students, such as calculating the mass of a black hole, rotation curves and lensing as evidence for dark matter. There are also videos on exoplanet detection techniques (Doppler method in more detail – estimating orbital radius, mass, surface temperature). Last is a set of 28 videos under ‘Astrobiology’. This is an introduction to astrobiology, and is at a more basic level (no mathematics). These feature topics such as the history of life on Earth, habitable zone, abiogenesis, panspermia, Urey Miller experiment, searching in our own solar system, exoplanets, SETI, aliens and UFOs.”
Another resource is the Silicon Valley Astronomy Lectures, featuring astronomers giving non-technical lectures on recent developments in astronomy, which are now available on their own YouTube Channel, at:
The lectures were taped at Foothill College near San Francisco and co-sponsored by NASA’s Ames Research Center, the SETI Institute, and the Astronomical Society of the Pacific. The speakers include coauthor, Alex Filippenko, talking about black holes.

From the International Astronomical Union’s Newsletter of the Commission 46 on the Teaching of Astronomy (coauthor Pasachoff was president of the Commission):  An article in the American Journal of Physics, June 2013 (V81, pp. 414-420) describes a useful set of programs that illustrate techniques of analysis in modern cosmology, allowing students to “discover” the acceleration of the Universe. The authors are Jacob Moldenhauer, Larry Engelhardt, Keenan M. Stone, and Ezekiel Shuler from the Department of Physics and Astronomy, Francis Marion University, Florence, South Carolina, USA. Here is the abstract of the article: “We present a collection of new, open-source computational tools for numerically modeling recent large-scale observational data sets using modem cosmology theory. These tools allow both students and researchers to constrain the parameter values in competitive cosmological models, thereby discovering both the accelerated expansion of the universe and its composition (e.g., dark matter and dark energy). These programs have several features to help the non-cosmologist build an understanding of cosmological models and their relation to observational data, including a built-in collection of several real observational data sets. The current list of built-in observations includes several recent supernovae Type-Ia surveys, baryon acoustic oscillations, the cosmic microwave background radiation, gamma-ray bursts, and measurements of the Hubble parameter. In this article, we discuss specific results for testing cosmological models using these observational data.”

The software described in the article, called CosmoEJS, is freely available online from ComPADRE.

On December 4, 2013, the U.S. House of Representatives Committee on Science, Space, and Technology met for a hearing on “Astrobiology: Search for Biosignatures in our Solar System and Beyond”.


Credit: NASA/Ames/JPL-Caltech

The hearing’s purpose was to examine astrobiology research and the search for signs of life in our Solar System and beyond. It included a general assessment of the multi- and interdisciplinary nature of astrobiology research, including the role astrobiology plays in formulating NASA space missions. It also examined the techniques and capabilities necessary to determine the potential for the existence of biosignatures within our Solar System.

With the discovery of potential Earth-like planets outside of our Solar System, the committee heard three experts discuss what methods are being used to determine if any of these planets may harbour life and explored existing and planned astrobiology research strategies and roadmaps.

Links: House Committee on Science and Technology website, including the witnesses’ testimony in transcript form and an archived webcast of the proceedings.

The European Research Council (ERC) has awarded 14 million euros (around $19 million) to a team of European astrophysicists to construct the first accurate image of a black hole. The team will test the predictions of current theories of gravity, including Einstein’s general theory of relativity. The funding is provided in the form of a synergy grant, the largest and most competitive type of grant of the ERC. This is the first time an astrophysics proposal has been awarded such a grant.

The team, led by investigators at the University of Nijmegen, the Max Planck Institute for Radio Astronomy, and Goethe University in Frankfurt, hopes to measure the shadow cast by the event horizon of the black hole in the center of the Milky Way, find new radio pulsars near this black hole, and combine these measurements with advanced computer simulations of the behavior of light and matter around black holes as predicted by theories of gravity. They will combine several telescopes around the globe to peer into the heart of our own galaxy, which hosts a mysterious radio source called Sagittarius A* which is considered to be the central supermassive black hole. (See p. 383 and Section 15.5, p. 391.)


Credit and © M. Moscibrodzka & H. Falcke, Radboud-Universität Nijmegen

Black holes are notoriously elusive with a gravitational field so large that even light cannot escape their grip. The team plans to make an image of the event horizon – the border around a black hole which light can enter, but not leave.  The scientists want to peer into the heart of our own galaxy, which hosts a mysterious radio source called Sagittarius A*. The object is known to have a mass of around 4 million times the mass of the Sun and is considered to be the central supermassive black hole of the Milky Way.

As gaseous matter is attracted towards the event horizon by the black hole’s gravitational attraction, strong radio emission is produced before the gas disappears. The event horizon should then cast a dark shadow on that bright emission. Given the huge distance to the center of the Milky Way, the shadow is equivalent to the size of an apple on the Moon seen from Earth. By combining high-frequency radio telescopes around the world, in a technique called very long baseline interferometry (VLBI), even such a tiny feature is, in principle, detectable.

In addition, the group wants to use the same radio telescopes to find and measure pulsars around the very same black hole. Pulsars are rapidly spinning neutron stars, which can be used as highly accurate natural clocks in space. While radio pulsars are found throughout the Milky Way, surprisingly none had been found in the center of the Milky Way until very recently.

On December 14, 2013, China became the third nation to successfully land a spacecraft on the Moon, a so-called ‘soft’ landing. This is also the first such lunar landing in 37 years.

Credit: Wang Jianmin/XinHua, via AP

The Chang’e-3 landing craft carried a solar-powered, robotic rover called the Jade Rabbit (Yutu in Mandarin Chinese), which emerged several hours later to begin exploring Sinus Iridum, or the Bay of Rainbows, a relatively smooth plain formed from solidified lava. According to a Chinese legend, Chang’e is a moon goddess, accompanied by a Jade Rabbit that can brew potions that offer immortality.


Credit: Chinese National Space Administration, Xinhuanet

A later Chang’e mission, perhaps sometime before 2020, is intended to bring back rocks and other samples from the Moon, and that will need a larger craft capable of sending a vehicle back to Earth. That mission will also need a more powerful launch rocket, which China is also developing.

Links: NY Times article, BBC News report, APOD coverage.

The Fermi Gamma-ray Space Telescope celebrates 2000 days of orbiting Earth this week with a new map of the gamma-ray sky, published on APOD on December 6, 2013.


Credit: International Fermi Large Area Telescope Collaboration, NASA, DOE

For an Earth-orbiting gamma-ray telescope, Earth is actually the brightest source of gamma-rays, the most energetic form of light. Gamma-rays from Earth are produced when high energy particles, cosmic rays from space, crash into the atmosphere. While that interaction blocks harmful radiation from reaching the surface, those gamma-rays dominate in this remarkable Earth and sky view from the orbiting Fermi Gamma-ray Space Telescope’s Large Area Telescope. The image was constructed using only observations made when the center of our Milky Way galaxy was near the zenith, directly above the Fermi satellite. The zenith is mapped to the center of the field. The Earth and points near the nadir, directly below the satellite, are mapped to the edges of the field resulting in an Earth and all-sky projection from Fermi’s orbital perspective. The color scheme shows low intensities of gamma-rays as blue and high intensities as yellowish hues on a logarithmic scale. Our fair planet’s brighter gamma-ray glow floods the edges of field, the high intensity yellow ring tracing Earth’s limb. Gamma-ray sources in the sky along the relatively faint Milky Way stretch diagonally across the middle.

In this short article for The Conversation, Helen Maynard-Casely summarizes current efforts in exploring the Solar System, with missions underway to nearly every planet (and dwarf planet, Pluto).

Only a small bit of the sun-grazing Comet ISON has apparently survived its perihelion passage on Thanksgiving Day (November 28th), so no grand display of a comet with a tail visible to the naked eye will be seen.  Still, the comet has given a lot of scientific data through spectra from ground-based telescopes and views from a variety of spacecraft. (See Section 8.3)

Comet ISON, which has orbited the Sun among the objects of the Oort cloud for almost 4.5 billion years, perhaps as much as a light-year away from the inner Solar System, has remained largely untouched since the time of the Solar System’s formation. Since it was first detected nearly a year ago, astronomers hoped that its passage would offer a unique glimpse of the state of our Solar System in its earliest moments.

Links: Updates from Sky & Telescope magazine; ISON movie from SOHO’s coronagraph; ISON image gallery from; NASA Comet ISON Observing Campaign website.