How was the world created? People have asked this ever since they could ask anything, and answers have come from all sides: from religion, tradition, philosophy, mysticism... and science. While this does not seem like a problem amenable to scientific measurement, it has led scientists to come up with fascinating ideas and observations: the Big Bang, the concept of inflation, the fact that most of the world is made up of dark matter and dark energy which we can not perceive, and more.
Of course scientists cannot claim to know the definitive truth. But we can approach the question from a scientific viewpoint and see what we find out. How do we do that? First, we look to the data. Thanks to modern technology, we have much more information than did people of previous ages who asked the same question. Then we can use scientific methods and techniques to analyze the data, organize them in a coherent way and try and extract an answer. This process and its main findings will be described in the article.

Follow the adventures in the life of a Welsh astrophysicist sent into exile to a small island in the middle of the ocean. A blog by a scientist that almost certainly won't be about science, but will be very facetious.

Duncan is a postdoctoral research fellow at the Institute for Astronomy, part of the University of Edinburgh. His research focuses on numerical simulations of protoplanetary discs, the spawning grounds of the planets. He came to fame (and infamy) through a research sideline – numerical astrobiology. His work on attempting to model life in the Galaxy became a hot topic in the blogosphere, and was picked up by the major news networks across the globe.

The purpose of this web site is to act as a community knowledge base for performing astronomy research with Python. It provides lists of useful resources, a forum for general discussion, advice, or relevant news items, collecting users' code snippets or scripts, and longer tutorials on specific topics. The topics within these pages are presented in a list view with the ability to sort by date or topic. A traditional "blog" view of the most recently posted topics is visible from the site Home page.

APLpy (the Astronomical Plotting Library in Python) is a Python module aimed at producing publication-quality plots of astronomical imaging data in FITS format. The module uses Matplotlib, a powerful and interactive plotting package. It is capable of creating output files in several graphical formats, including EPS, PDF, PS, PNG, and SVG.

Emission lines provide a powerful tool to study the physical properties and chemical compositions of astrophysical objects in the Universe, from the first stars to objects in our Galaxy. The analysis of emission lines allows us to estimate the star formation rate and initial mass function of ionizing stellar populations, and the properties of active galactic nuclei. This book presents lectures from the eighteenth Winter School of the Canary Islands Astrophysics Institute (IAC), devoted to emission lines and the astrophysical objects that produce them. Written by prestigious researchers and experienced observers, it covers the formation of emission lines and the different sources that produce them. It shows how emission lines in different wavelengths, from ultraviolet to near infrared, can provide essential information on understanding the formation and evolution of astrophysical objects. It also includes practical tutorials for data reduction, making this a valuable reference

We describe an image analysis supervised learning algorithm that can automatically classify galaxy images. The algorithm is first trained using a manually classified images of elliptical, spiral, and edge-on galaxies. A large set of image features is extracted from each image, and the most informative features are selected using Fisher scores. Test images can then be classified using a simple Weighted Nearest Neighbor rule such that the Fisher scores are used as the feature weights. Experimental results show that galaxy images from Galaxy Zoo can be classified automatically to spiral, elliptical and edge-on galaxies with accuracy of ~90% compared to classifications carried out by the author. Full compilable source code of the algorithm is available for free download, and its general-purpose nature makes it suitable for other uses that involve automatic image analysis of celestial objects.

The following tables list the general filters available for general use, together with their sensitivites. The transmission curves of each filter are available as plots or ASCII lists if indicated in the respective columns.

"Astrophysics Updates" is intended to serve the information needs of professional astronomers and postgraduate students about areas of astronomy, astrophysics and cosmology that are rich and active research spheres. Observational methods and the latest results of astronomical research are presented as well as their theoretical foundations and interrelations. The contributed commissioned articles are written by leading exponents in a format that will appeal to professional astronomers and astrophysicists who are interested in topics outside their own specific areas of research. This collection of timely reviews may also attract the interest of advanced amateur astronomers seeking scientifically rigorous coverage.

Proposal for a Cosmological Tests with Ly$\alpha$ emitters.

The atlas contains about 7600 stellar atmosphere models for a wide
range of metallicities, effective temperatures and gravities. These new
LTE models have improved opacities and are computed with a finer
wavelength and temperature resolution than the previous Buser-Kurucz
atlas installed in the CDBS (crgridbk). The microturbulent velocity is
2 km s^{-1}.

We present stellar population modeling results for ten newly discovered Lyman alpha emitting galaxies (LAEs), as well as four previously known LAEs at z ~ 4.5 in the Chandra Deep Field-South. We fit stellar population models to these objects in order to specifically learn if there exists more than one class of LAE. Past observational and theoretical evidence has shown that while many LAEs appear to be young, they may be much older, with Lyα equivalent widths enhanced due to resonant scattering of Lyα photons in a clumpy interstellar medium (ISM). [...]

We present a rest-frame ultraviolet analysis of ~120 z~3.1 Lyman Alpha Emitters (LAEs) in the Extended Chandra Deep Field South (ECDF-S). Using Hubble Space Telescope (HST) images taken as part of the Galaxy Evolution From Morphology and SEDS (GEMS) survey, Great Observatories Origins Deep Survey (GOODS), and Hubble Ultradeep Field (HUDF) surveys, we analyze the sizes of LAEs, as well as the spatial distribution of their components, which are defined as distinct clumps of UV-continuum emission.

Welcome to my Galaxy Luminosity Function Engine. You can use the form below to create your own B-band luminosity function (LF) of a volume-limited galaxy population. The assumption is that the shapes of the type-specific LF of ellipticals (E), lenticulars (S0), spirals (Sp), dwarf irregulars (dIrr), and dwarf ellipticals (dE) are invariant of the environment and thus the observed variation of the overall LFs from galaxy clusters to the field has its origin in the different type mixtures (known as the morphology-density relation).

Fundamental Astronomy is a well-balanced, comprehensive introduction to classical and modern astronomy.

Aimed at the science student market, this book makes an excellent textbook, both for undergraduates and for graduates just beginning their courses who are looking for an overview. It covers the whole field of modern astronomy in a clear and concise way that is rare in modern introductory-level textbooks.

While emphasizing both the astronomical concepts and the underlying physical principles, the text provides a sound basis for more profound studies in the astronomical sciences.

The way galaxies assemble their mass to form the well-defined Hubble sequence is amongst the most debated topic in modern cosmology. One difficulty is to link distant galaxies to those at present epoch. We aim at establishing how were the galaxies of the Hubble sequence, 6 Gyrs ago. We intend to derive a past Hubble sequence that can be causally linked to the present-day one. We selected samples of nearby galaxies from the SDSS and of distant galaxies from the GOODS survey. We verified that each sample is representative of galaxies. We further showed that the observational conditions necessary to retrieve their morphological classification are similar in an unbiased way. Morphological analysis has been done in an identical way for all galaxies in the two samples. We found an absence of number evolution for elliptical and lenticular galaxies, which strikingly contrasts with the strong evolution of spiral and peculiar galaxies. Spiral galaxies were 2.3 times less abundant in the past ...