Questions Series: How do we know the size of the Universe?

A set of questions I get from kids and adults alike while doing my Astronomy in Action planetarium shows consists of the following: Does the Universe have an end? How big is the Universe? Where is the center of the Universe? What is the ‘Observable Universe?’ How is it different from just saying ‘the Universe?’ […]

Holiday Lights Make Cities Visibly Brighter from Space

With the extra lights shining in cities across the world at this time of year, we are outputting a significant number of photons into Space.  So many that Satellites in orbit have been able to see the difference.  In the maps below, the areas in green are locations where the brightness has increased by as […]

Top 5 comet breakups in History

When comets breakup it can be an emotional time for Astronomers, amateur and professional alike.  Though not like a breakup with a significant other, we get our hopes up that the next comet will be a comet of the century.  We do this because comets are very unpredictable, and any given close approach to Earth […]

An Explosive new Podcast

A Commander Chris Hadfield returns home tonight, the York Universe crew will be focusing on his voyage with a special show, featuring talk of the incredible and inspiring exploits of the first Canadian commander of the International Space Station.  Featured in this episode will be an interview with one of the newest Canadian Astronauts, Jeremy Hansen. […]

Fairwell fair Herschel

The Hershel Observatory, an ESA telescope for which NASA helped build instruments and process data, has stopped making observations as it has finally run out of its liquid Helium coolant, as expected.  This is a good time to remember the multitude of data that a space based telescope can churn out, and the incredible scientific […]

Age of the Universe off by 100 million years

Okay so 100 million years seems like a big mistake on the part of Astronomers, but in the astronomical community its a small adjustment.

Highest detail map of the CMBR ever produced Credit: ESA/Planck

Today the most detailed map of the CMBR ever captured was released by the Planck telescope group at the ESA.  Based on 15.5 months of data, it shows the tiny temperature variations that were present when the universe had a temperature of 2700 degrees Celsius and an age of just 380,000 years (trust me that’s small on astronomical scales).  This is the point when the dense soup of protons and electrons formed hydrogen atoms, and the universe became transparent.

As the universe has expanded the light has stretched out to microwave wavelengths and now has a temperature of 2.7 degrees above absolute zero, -270 Celsius   The tiny temperature fluctuations on the order of millionths of degrees visibly correspond to the structure that would eventually map out the structure of galaxies and galaxy clusters throughout the universe.

The estimate of the age of the universe is now more precise as well, since the CMBR measurements give precise constraints to the Hubble constant, used in the Lambda-CDM model of the universe to generate the time passed since the big bang.  The adjustment brings the universe’s age to 13.82 billion years, 100 million years older than previously thought.  This seems like a large difference, but as I said before, on astronomical scales we were in the right zone so its not too surprising.

However, some surprise did arise from the new map, pointing to the (known) conclusion that we do not understand the universe on larger scales.  On small scales the standard model is correct, which says that CMBR temperature differences are caused by random quantum fluctuations, but on large scales this model falls short, suggesting that there is more to the big picture of understanding the universe.  One such shortcoming is that a cold spot in the CMBR is much larger than expected from the standard model.

This is not a big surprise however, as physicists are aware that more theory is needed to explain the universe, since the standard model can’t explain either dark matter or dark energy, the two largest sources of’stuff’ in the universe.

Let’s think about that for a second.  We have no clue what most of the universe is made of.  And we don’t even have a really complete picture of the stuff we do know.  Astronomy and Cosmology are still wide open fields.

Closest Stellar System Chills Out

Alpha Centauri.  Not only is it an alien in Dr.who, a strategy game released in 1999, and an album released by the German electronic band tangerine dream, but it’s the brightest star in our closest stellar system.  Named for being the brightest star in the constellation Centaurus in the southern sky, its a little over 4 light years away from Earth, and is very similar to our sun in terms of size, age, mass, composition, and temperature. Here is a great infographic from

Scientists have recently discovered that Alpha Centauri shares yet another resemblance to our home star: It has a strange, cooler layer in its atmosphere.

Star Layers, Credit:ESA
Layers of the Stellar Atmosphere Credit: ESA


The surface of the sun, called the photosphere, has a temperature of about 5700 Kelvin.  That’s about as hot as flames in the ol’ fireplace.  The center of the sun, where all the fusion happens, is upwards of 15 million Kelvin.  But further out past the photosphere we reach the corona, a powerful radiative zone where the temperature can reach about 2 million Kelvin.  We see the solar corona during a total eclipse of the sun.  Although the temperatures vary slightly in Alpha Centauri, it shares a similar pattern.

So why the drop in temperature? Or rather why the boost in temperature farther out? Astronomers aren’t completely sure, though they think its due to the same phenomenon that gives rise to solar flares: Twisting of magnetic field lines.

The important point is that this is the first time we’ve observed this phenomenon in a star other than the sun.  Is it present in all stars? Or only sun-like stars? Further study of Alpha Centauri and its similarities and differences when compared to the sun will give us an idea of the answers to these questions, and surely will result in a lot more questions, as is the way of science.

Return of the Dragon

This morning was the launch of the second SpaceX dragon capsule mission, officially designated mission CRS-2.  It launched at 10:10am today, Friday, March 1st from Cape Canaveral space launch complex 40.

A bit of background on Dragon: 

The two-stage rocket uses 9 engines to power the first stage out of the atmosphere, before the single rocket stage 2 takes the capsule the rest of the way.  The 14.4 foot tall dragon capsule is capable of carrying more than 7000 lbs of cargo split between pressurized and unpressurized sections.

On March 2nd, Astronauts will use the CanadaArm 2 to grab onto the capsule and unload the contents.  The crew will also load more than 2600 lbs of experiment samples and equipment for return to Earth during a scheduled parachute-assisted splashdown off the coast of California on March 25th.

This is the second of at least 12 planned missions by SpaceX for commercial resupply purposes for NASA.

Mission Update: The rendezvous with the International Space Station (ISS) will be delayed slightly, due to an issue with a propellant valve after achieving orbit.  The solar arrays have been deployed, though for a time only one of the three thruster pods was responsive.  At this point, according to the twitter feed of Elon Musk, CEO of SpaceX, a second thruster pod is up and running, and the craft has moved from free orbit to active control, and can now begin a burn to rendezvous with the ISS.

4:04pm – Thurster pods 1 through 4 all up and running, preparing to raise orbit to catch the ISS!