In addition to this, Planck is also undertaking a few other observations of nearer things, such as parts of our own Milky Way galaxy.  As the most sensitive instrument of its kind, it can see things with a greater clarity, resolution and range of wavelengths than ever before, and scientists have several targets selected for it.

The rocket that took Planck into space was an Ariane 5, the ESA’s standard launch vehicle.  The launch took place on May 14, 2009, from the ESA spaceport in Kourou, French Guiana.  As a cost-saving measure, Planck was launched along with another probe, the Herschel infrared observatory.  These two probes separated from their launcher soon after reaching space.  Both of them were sent on a course that would eventually lead them to the second Lagrangian point (L2), situated about 1.5 million km. from Earth in the opposite direction from the sun.

These two probes will operate independently of each other, but the science they  do will be complementary.  The Herschel infrared observatory is also an interesting subject, and will be examined further in a future article at this site.  For now, we will concentrate on Planck.

The Planck satellite weighed about 1900 kg. at launch, and has a boxy shape about 4.2 meters on a side.  It is equipped with a 1.5-meter-wide mirror which focuses radiation from the sky and sends it to two detectors known as the Low Frequency Instrument and the High Frequency Instrument.

The Low Frequency Instrument (LFI) performs observations of the microwave sky in the range of frequencies from 27 to 77 GHz.  It is composed of 22 tuned radio receivers which work like the transistors in a radio, amplifying the signal and converting it into a voltage.  The High Frequency Instrument (HFI) performs observations in the range from 84 GHz to 1 THz.  It has 52 bolometric detectors , devices capable of measuring very small amounts of heat energy.  The results from these two instruments are complementary, and go together to form the total mission results.

The instruments are very sensitive to heat, and the probe’s designers had to include a cooling system and various other measures to ensure a stable, low temperature.  In fact, the reason why Planck orbits the sun at the L2 point, rather than orbiting Earth, is that both Earth and the moon give off too much heat.  Planck had to get some distance away from them, or their heat would have spoiled the observations.

Planck is equipped with its own thrusters, and these were used for three course correction maneuvers.  The third of these maneuvers took place on July 2, and injected the probe into its orbit around the L2 point.

Because of the temperature constraint, it was necessary to put the probe through a cooling process before it could go into operation.  The instruments hit their lowest temperature, 0.1K above absolute zero, in the first week of July.  During the cooling period, all of the satellite’s subsystems were also turned on and tested.

Planck was designed to give answers to some of the most fundamental questions in cosmology: how did the universe begin, how did it evolve to the state that it is in today, and how will it evolve in the future?  The Cosmic  Microwave Background  carries information about the processes that took place in those early moments of existence, and by analyzing it, scientists can look through a window in time, to the moment right after creation.

This information takes the form of tiny temperature fluctuations in the CMB, about a millionth of one degree.  This is the equivalent of detecting the body heat of a rabbit sitting on the moon from Earth.

Planck’s first task was the First Light Survey, which was really just a chance to check the sensitivity of the instruments and make sure they could perform as expected.  The scientists were delighted to find that the quality of the data was excellent.

Since then, Planck has been working on its first All-Sky Survey.  This began in mid-August 2009, and is being completed now.  As of mid-March 2010, 98% of the sky had been observed by Planck, and 100% sky coverage is expected by late May 2010.

However, before the raw data can be turned into sky maps of the CMB, it will require a lot of delicate adjustments and careful analysis.  About two years will be need to refine the information and obtain the scientific results.  Even then, the resulting maps will provide decades of work for cosmologists and astrophysicists as they continue to study and analyze them.

One of the things they’ll be looking for will be confirmation of the current theory of how the universe formed.  This is one of those sticky moments in science when the scientific authorities have a theory that explains everything beautifully, but they don’t have a shred of evidence to support it- or to disprove it, for that matter.  The theory is called the inflation model, and the condensed version runs something like this:

(What came before the Big Bang, we have no idea.  All of our theories of the evolution of the universe deal with what happened after that event, and if anything came earlier, we probably will never know about it.)

The universe begins as an extremely small point.  During the first millionth of a second of its existence, it rapidly expands, or “inflates.”  After this initial burst of expansion, it continues to grow at a slower rate, and as it grows, the thermal energy which it contains becomes spread out over a larger area.  This means that the universe cools as it expands.

When the temperature of the universe drops to 1000 GeV (about 10 million million degrees) the natural forces appear: gravity, electromagnetism, and the strong and weak nuclear forces.  Quarks, the things that will form matter, appear and wander freely through the universe. As the universe keeps cooling, these quarks will eventually combine to form protons and neutrons, but it will still be too hot for them to capture electrons and make real elements.  Since electrons aren’t being captured to form atoms, they are free to interact with photons (light particles).  Because of this, a photon can’t travel very far without encountering an electron, and light does not propagate freely.  Because of this, the universe is dark.   It is only after 300,000 years that the universe cools enough to allow protons to capture electrons and form hydrogen atoms, which finally allows light to propagate freely. Light comes to the universe, and that first burst of light is the Cosmic Microwave Background.

Matter begins to form clots due to gravity, and as these clots grow, the universe takes on a more familiar appearance.  Stars form, and these form galaxies.

Fast-forward to today, and we see around us a universe filled with structures.  Galaxies form clusters, clusters form sheets and streamers spanning vast distances.  Where did all the structure come from?  If the universe all expanded out of one tiny point, why isn’t it uniform?  Why is matter gathered in some areas, while it seems to be more diffuse in other places?

The inflation theory explains the elaborate structures in the universe, which result from an uneven distribution of matter, by saying that they are the expansion of tiny variations in the original point from which it all expanded, and the expansion happened so suddenly that those variations were preserved, in vastly greater size, as the unevenness of matter in the universe today.

In other words, there has always been an unevenness in the distribution of matter and energy (as well as dark matter and dark energy).  This goes all the way back to the first instant of expansion, and since the CMB comes from close to the first moment (300,000 years is not very long in universal terms) it should have this unevenness, too.  It should also carry various other information from that early time, which Planck’s instruments can coax from it.  As a snapshot of the universe at a young age, it should have things to tell us about how the universe started, and how it got like it is today.

These are the kind of cosmic questions that Planck was designed to address.  Along the way, it will also do some viewing closer to home.  In fact, just a few days ago, the ESA released spectacular pictures taken by Planck showing filaments of cold dust only a few hundred lightyears away.  In addition to its work relating to the CMB, Planck will be doing studies of this nature, investigating structure and evolution on a galactic scale.

Planck is just getting started, and the clarity and resolution of the data so far promises great things for the future.  The questions that it addresses are of the most fundamental nature: how did it all begin, and how did it get like it is now?  You can’t get more cosmic than that.

As new data comes in from Planck, you can find it here.

Sources:

ESA Space Science: Planck Overview at website of European Space Agency:  esa.int/esaSC/120398_index_0_m.html

ESA Planck homepage at website of European Space Agency:  esa.int/SPECIALS/Planck/index.html

“Planck at a Glance: ESA’s Microwave Observatory” at website of European Space Agency:  esa.int/SPECIALS/Planck/SEMWN20YUFF_0.html

ESA Planck: Science Objectives at website of European Space Agency:  esa.int/SPECIALS/Planck/SEM0P20YUFF_0.html

ESA Planck: Planck Highlights at website of European Space Agency:  esa.int/SPECIALS/Planck/SEMKO20YUFF_0.html

ESA Planck: Instruments at website of European Space Agecny:  esa.int/SPECIALS/Planck/SEMBU20YUFF_0.html

ESA Planck: Launch and Early Operations at website of European Space Agency:  esa.int/SPECIALS/Planck/SEMB030YUFF_0.html

ESA Science and Technology: Planck at website of European Space Agency:  sci.esa.int/science-e/www/area/index.cfm?fareaid=17

ESA News: “Planck Sees Tapestry of Cold Dust” at website of European Space Agency:  esa.int/esaCP/SEMMN9CKP6G_index_0.html

ESA Space Science: “So How Everything Start?— a Timeline for the Universe” at website of European Space Agency:  esa.int/esaSC/SEMC6TS1VED_index_0.html

The Spitzer Telescope was the final mission of NASA’s Great Observatories Project which launched a family of four observatories into space. The most famous and well known of these is probably the Hubble Telescope and the program also included the Compton Gamma-Ray Observatory and the Chandra X-Ray Observatory.

The Spitzer Telescope was launched into space in August 2003. It was originally named the Space Infrared Telescope Facility and, in accordance with NASA tradition, was renamed the Spitzer Telescope following the successful demonstration of its operational capabilities. The telescope is 0.85m in size and three science instruments were also included as part of the mission. These included an Infrared Array Camera, an Infrared Spectrograph and a Multiband Imaging Photometer.

The telescope obtains images by detecting the infrared energy which is radiated by objects in space and this required that it be cooled to near absolute zero using liquid helium. With this requirement it was expected that the functional life of the telescope would be around 5 years. After this length of time it was expected that the liquid helium would become exhausted and the science instruments would be of no further use although the telescope itself would still be operational.

The event at the Adler Planetarium in Chicago demonstrated that the mission has been a great success. The image of the Milky Way the telescope has produced is one of the most stunning views of the galaxy that has ever been seen. To produce the final image data from two of the three onboard instruments was collected and processed by teams involved in the mission. These were the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) team which used data from the Infrared Array Camera and the Multiband Imaging Photometer for Spitzer Galactic Plane Survey Legacy (MIPSGAL) team which used data from the Multiband Imaging Photometer.

The image these teams created covers a huge area and was made by stitching together an incredible 800,000 individual pictures. The resulting masterpiece is 120 feet long by 3 feet wide at the sides and the width increases to 6 feet in the centre. It is the highest-resolution and largest image of the Milky Way ever created and shows the galaxy in stunning detail. The new image is detailed enough to show clusters of stars where previous pictures had shown only a single source of light. The leaders of the two teams involved in the work attended the event to unveil the image and they also gave short presentations about the work involved in creating it.

It is considered that the image is probably the best view we will have of the Milky Way for the foreseeable future. It will assist scientists studying the galaxy and should help them in better understanding some of the processes involved in its formation. The picture is to remain as a permanent exhibit at the Adler Planetarium and a trip to see it is definitely worth doing if you visit Chicago.

The art/science of studying the stars was engaged by several ancient populations like Maya, Incas, Egyptians and Greeks, and soon grew in importance to the point where those who practiced it were highly regarded and respected in their own society. The reason for this is evident: this science could provide, even from its first, rudimentary structure, an explanation to phenomena strictly connected to their life, such as the alternating of day and night or the cycle of seasons, and provided an essential instrument for activities such as agriculture and navigation.

The history of Astronomy is in part — from its origins to the invention of the telescope by Galileo Galilei, in 1610 — also the history of astrology. In prehistoric ages, the most advanced tribes were familiar with the motion and trajectories of just a few, visible objects like the sun, the moon and some of the brightest stars. The most commonly cited example of such knowledge is the Stonehenge complex, residing in Great Britain, which is thought to have served as a monumental calendar.

Chinese astronomy was born before 2000 BC and is still cited nowadays for its great tradition of carefully, a-critic documentation. From the documents in our possession we know that in their time they were already aware of events such as the passage of comets, or even the explosion of a Supernova star.

A few civilizations in central America also reached astonishing results, but unfortunately they didn’t manage to share they knowledge with other populations. Maya and Inca tribes would often build pyramids and temples, which were devoted to the Gods of the Sky. Their religion was strictly related to the planet Venus and, based on estimations of its motions, they managed to create an incredibly precise astronomical calendar, finding out, among other things, that the planet would accomplish five complete orbital revolutions in the time span of exactly 584 days.

Babylonians soon showed exceptional knowledge in the matter of astronomy, which would later be inherited by Egyptians and Indians. In their case, the desire to perfect this science at all costs came, rather than an actual need, from skeptical reasons that linked the motion of stars and planets to good or bad luck (solar and lunar eclipses were thought to bring extremely bad luck, and this conception would persist until relatively recent times). Even lacking any sort of precise instrumentation, Babylonians managed to find out many things about the apparent motion of planets, basing their observation on the position of a few bright stars on the sky: they therefore discovered the orbital revolution time of many planets, among which Venus, Mars, Jupiter and Saturn, only mistaking by a few days, and reporting the results of their calculations on special tables, most of which are well-preserved and can still be seen now in astronomical museums.

Egyptians’ immense and astonishing knowledge regarding astronomy relies, once more, on their ability to forge precise calendars describing the motion of stars and planets. As their life cycle was strictly linked to that of the Nile river, astronomy was given a central role by this society from the very beginning. Around 3000 BC, Egyptians were already used to dividing their day and night time in regular intervals of 12 parts each: day time would be measured by sundials, while night time would be measured by observing the relative position of 24 bright stars. Measuring this way, their ‘hours’ would have a different duration depending on the season, but still averaging 60 minutes each.

It was only with Greek astronomy, though, that a stress was posed on developing theories that would explain the birth of the Universe and its mechanics: Anaximander thought the planet Earth was a cylinder at the center of the Universe, while the stars would rotate around it in all directions; Plato had at a first time a theory, extremely advanced for its time, that put the Sun at the center of the Universe, but he later withdrew it to favor an Earth-centric theory similar to that of Anaximander; Eudoxus of Cnidus, finally, advanced a theory that was later approved by Aristotle, according to which the Universe was made of concentric spheres, rotating one inside another, where the Earth would be in the center.

The Aristotle conception of the structure of the universe was meant to last, with minimal variations, until the year 1500 AD, when Nicolaus Copernicus — which many consider the father of modern astronomy — advanced a theory that put the Earth orbiting in perfect circles around the Sun, together with all the other planets: this approach could in fact solve many of the contradictions that those who supported Aristotle had to face. A few decades later, John Kepler refused yet another innovative model of the universe from his mentor Tycho Brahe, and later became famous for formulating the three laws of star mechanics that were named after him, which are considered valid still nowadays.

In 1610, Galileo Galilei invented the telescope, after a long period of research and experimentation. As soon as he pointed it at the stars, a never seen before universe appeared in front of his eyes: the Moon had a surface full of craters, Jupiter was surrounded by four satellites, while the Milky Way suddenly appeared as nothing but a huge mass of countless stars. In 1632, after publishing his book ‘Dialogo sopra i due massimi sistemi del mondo’ [On the main two models of the Universe] in which he was openly exposing the results of his observations, he was forced by the Catholic Church to abjure not having made those discoveries.

A few decades later, while researching innovative techniques to build more and more powerful telescopes, an important debate took place between the scientist Huygens and Newton over the nature of light: the first said it was a wave, while the second thought it was made of physical ‘atoms’ (photons). The debate that was destined to be solved once and for all just a few decades ago (light is, indeed, both a wave and a physical object). Huygens studied advanced optics as well, and managed to build a telescope that could noticeably minimize the chromatic aberration in observations, which led him to discover Saturn’s rings and its moon, Titanus.

Just a few years later, Cassini and Romer found out that phenomena such as solar eclipses would happen just several minutes after they were expected: this led them to think that light could actually travel at a finite although extremely high speed, rather than to an infinite speed: their estimation put the speed of light at 230,000 km per hour (the actual speed of light is 300,000 km/h).

Starting from the 19th century, following the Industrial Revolution, the continuous development of innovative techniques and instruments for the observation of the sky led to a series of discoveries that quickly contributed to our knowledge. Nowadays, the main purpose of astronomy is to study the life cycle of stars and galaxies, the origin and future of the Universe, obscure objects like pulsars and black holes, and methods to measure interstellar distances with increased precision.