There are the Sketches of the four moons of Jupiter (Io, Europa, Ganymede and Callisto), as seen by Galileo
through his telescope.

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                                                 Source

The drawing depicts observations from the time period January 7 to 24, 1610.

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The above is the sequence of photographs taken by JunoCam aboard the Juno
spacecraft, in June 2016, of Jupiter and the motion of the four Galilean
moons, as the spacecraft approached the planet.

* There are 79 known moons of Jupiter.

** Jupiter has 4 rings.

Emojis of the cosmos

Pareidolia  is a psychological phenomenon in which the mind responds to a stimulus, usually an image or a sound, by perceiving a familiar pattern where none exists.

These are merely some images of stars and galaxies taken by the Hubble Space Telescope. But what do you see ?

One of the striking aspects of our solar system is that the orbital plane of all the planets are similar i.e Its like the following:

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                                                  Source

And not like so:

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But if you are puny human sitting on earth, how would one visualize this ? It’s easy!

Step out and look at the trajectory taken by the  sun and planets in the sky:

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                                                    Source

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You will notice that the trajectories taken by the sun and the planets are similar in the night sky.

This gives you a visual validation of the fact that the orbital plane of all the planets and the sun are similar. Just a little something that you may or may not have realized about the cosmos.

Go ahead, give it a shot and have fun!

* The ecliptic plane is the name given to the mean plane in the sky that the Sun follows over the course of a year; 

Van Gogh’s The Starry Night is a stunning painting that artistically brings out the effect of turbulence in our atmosphere on stargazing.

And this turbulence of air in addition to the effect of increasing refractive index causes the twinkling of stars:

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     Source: Enhanced Learning

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But if you are an astronomer trying to study the cosmos from the earth, this turbulence of air and twinkling of stars is a nightmare.

The last thing that you want the light that painstakingly took millions of years to get to the earth is be wiggled away from your telescope through refraction and turbulence.

Adaptive Optics

Have you ever seen time lapses like these of the Keck observatory with laser beams coming out of it ?

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Those lasers serve a purpose: to account for the atmosphere disturbances in the night sky in real time and correct the images that they observe dynamically.

This is known as Adaptive optics. This video by the RoyalObs explains the essence of Adaptive optics really well. Do watch it

With and Without Adaptive Optics

Prof. Andrea Ghez and her research team at UCLA whose research on what is at the center of our galaxy that was featured in our previous post has contributed a lot in using Adaptive optics for astronomical observations.

And using this technique, the following is the difference between capturing an image with and without adaptive optics.

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And it is with the aid of adaptive optics that the group was able to track the trajectories of the galaxies surrounding the proposed center of our galaxy to conclude that there is most likely a Super Massive Black Hole at the center of it.

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      Trajectories of stars surrounding the proposed center of our galaxy.

So, the next time you go out to gaze at the cosmos, just remember that whatever you are seeing in the night sky right now is through the looking glass of our beloved atmosphere.

And astronomers put in immense effort to nullify the dynamic atmospheric effects that it loves to entertain us with.

Have a great day!


All images/animations featured in this post were created by Prof. Andrea Ghez and her
research team at UCLA and are from data sets obtained with the W. M.
Keck Telescopes

Astronomy From 45,000 Feet

nasa:

What is the Stratospheric
Observatory for Infrared Astronomy, or SOFIA, up to?

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SOFIA, the
Stratospheric Observatory for Infrared Astronomy, as our flying telescope is called, is a Boeing 747SP aircraft
that carries a 2.5-meter telescope to altitudes as high as 45,000 feet.
Researchers use SOFIA to study the solar system and beyond using infrared
light. This type of light does not reach the ground, but does reach the
altitudes where SOFIA flies.

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 Recently, we used SOFIA to study water on Venus, hoping to
learn more about how
that planet lost its oceans
. Our researchers used a powerful instrument on
SOFIA, called a spectrograph,
to detect water in its normal form and “heavy water,” which has an extra
neutron. The heavy water takes longer to evaporate and builds up over time. By
measuring how much heavy water is on Venus’ surface now, our team will be able
to estimate how much water Venus had when the planet formed.

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We are also using SOFIA to create a detailed map of the Whirlpool
Galaxy
by making multiple observations of the galaxy. This map will help us
understand how stars form from clouds in that galaxy. In particular, it will
help us to know if the spiral arms in the galaxy trigger clouds to collapse
into stars, or if the arms just show up where stars have already formed.

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We can also use SOFIA to study methane on Mars. The Curiosity rover
has detected methane
on the surface of Mars. But the total amount of methane on Mars is unknown and
evidence so far indicates that its levels change significantly over time and
location. We are using SOFIA to search for evidence of this gas by mapping the Red
Planet with an instrument specially tuned to sniff out methane.

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Next our team will use SOFIA to study Jupiter’s icy moon Europa, searching for evidence of possible water plumes detected by the Hubble Space Telescope. The plumes, illustrated in the artist’s concept above, were previously seen in images as extensions from the edge of the moon. Using SOFIA, we will search for water and determine if the plumes are eruptions of water from the surface. If the plumes are coming from the surface, they may be erupting through cracks in the ice that covers Europa’s oceans. Members of our SOFIA team recently discussed studying Europa on the NASA in Silicon Valley Podcast.

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This is the view of Jupiter and its moons taken with SOFIA’s
visible
light guide camera that is used to position the telescope.  

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

In addition to conventional means of space observation like from space telescopes(like Hubble)

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and telescopes on the ground (like the Keck Observatory)

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SOFIA (or the flying telescope) is yet another tool that Astronomers use on a regular basis to study our universe.

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Resource: 
Inside NASA’s SOFIA Airborne Astronomical Observatory
 

Why does one image look better ?

Filters are very important in astronomical observation as they reduce glare and light scattering, increase contrast through
selective filtration, increase definition and resolution, reduce
irradiation and lessen eye fatigue.

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                                         Working of a magenta filter

Depending on which object you are looking, one chooses the appropriate filter. For instance the cover photo is without and withthe moon filter.

And on an amateur telescope they is how they are inserted.

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                                        Eye-piece filter (Source)

Telescopes like the Hubble have plenty of these filters stacked on them. You can find a list of the filters here.

Some popular filters commonly used are as follows:

Red –                           R

Green –                        V

Blue –                           B

Infrared –                      i’

Ultraviolet –                  u’

Hydrogen Alpha –       H-alpha

Oxygen III  –               OIII

LPR (Light Pollution Reduction)

Neutral Density filter  and so on…

Now here’s an image of the pillars of creation captured in various filters:

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Observe that the maximum number of stars are visible in the B, V and r’(infrared) filters. Therefore, combining these three image yields a standard image like the one you find online.

That being said, in our next post, we will run through a quick tutorial on how to access the Hubble archive and retrieve any image with any filter of your choice.

Have a good one!

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The Crab Pulsar (PSR B0531+21) is a relatively young neutron star. The
star is the central star in the Crab Nebula, a remnant of the supernova
SN 1054, which was widely observed on Earth in the year 1054.Discovered
in 1968, the pulsar was the first to be connected with a supernova
remnant.

The optical pulsar is roughly 20 km in diameter and the pulsar
“beams” rotate once every 33 milliseconds, or 30 times each second

The above video allows you to hear the signal from pulsar and the gif below that is the actual pulsar blinking taken with a high speed technique known as  Lucky Imaging .

Supernova Sorcerer: Robert Evans

fuckyeahphysica:

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                            Robert Evans with his reflecting telescope

Robert Evans is the world record holder for the most visual discoveries of Supernovae. Although he is a minister of the uniting church in Australia, he is better known in the Astronomy community as one of the ‘best Amateur Astronomers in the world.’

He is accredited for discovering 42 supernovas visually from his backyard!!

But, how on earth does he do it ?

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Having been looking at the cosmos for years on end, Evans has memorized the entire star field and the positions of the galaxies in the night sky.

And as a result of this, he can detect changes in the galaxy simply by looking at them through the telescope.

Why is this remarkable ?

This is truly remarkable for two pivotal reasons:

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A supernova is the explosion of a star. It is the largest explosion that takes place in space.

But spotting a supernova visually is extremely hard! 

To give a perspective on the intricacies of supernova hunting, here is a picture showing the night sky before and after a supernova in Messier-82.

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                                Supernova hunting in Messier-82

And secondly, he gave automated telescopes a run for their money. There are many telescope in recent times that automatically detect hundreds of supernovas every year.

But Evans managed to give them a tough fight in a battle against man and technology with his telescope sorcery.

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A note for budding astronomers

Why I find Evans to be extremely inspiring is because here is an amateur astronomer doing quality contributions to Astronomy in his backyard and with not so fancy equipment.

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Just shows how far passion and perseverance can take you in science.

Be limitless! Have a great day!

Yesterday’s post: Spectacular time-lapse from birth to death of a Supernova

This week on FYP! – Earth’s rotation

ICYMI we have been talking about Earth’s rotation for the past week on FYP!

We started off by asking the simple question: ‘Why did the Earth start spinning in the first place?

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And how has this rotation been affected by the moon over the course of centuries.

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But this did not give us any understanding for why the axis of rotation is inclined  by 23.5 degrees.

This is where we were introduced to the The Giant Impact Hypothesis which suggested that the Moon formed out of the debris left over from a collision between Earth and an astronomical body the size of Mars, approximately 4.5 billion years ago

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Now one of the consequences of living on a rotating object is that it flattens at its poles. The name given to such a flattened object is an oblate spheroid. We understood this using a simple experimental setup:

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Leaving all that aside, it was strongly believed by people for a really long time that it were the heavens that moved and not the earth.

It took a lot of debate among philosophers to come to the conclusion that it was indeed the Earth that was rotating. We looked at one such remarkable argument given by Galileo

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Having made this journey so far, we finally discussed how humans found a way to utilize the fact that we are on a rotating oblate spheroid to quench our thirst for the ecstatic understanding of the unknown.

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Are the heavens moving or are we?

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In the previous series of posts, we discussed about the key role that a rotating earth plays in space shuttle launches and quickly skimmed through why the earth began to rotate in the first place.

But in the 21st century, there are many experiments  (Coriolis effect,  Foucault’s pendulum ,etc, etc) that you can do to convince yourself that the Earth is indeed rotating.

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                                             ISS Live Stream

But back in the days of Galileo it was still debatable whether Earth was rotating or not. 

Why does a ball thrown straight up in the air fall to the same place on the ground ?

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One
of the profound Aristotelian arguments against the rotation of the
Earth was that if the Earth were rotating, a thrown ball/arrow would not
land in the same place that it was thrown.

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This was believed so
because, by the time the projectile traverses its path the Earth would
have moved by a certain distance. Hence, the ball would never land at
the same place it was thrown.

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Take a second to think about this. Can you come up with an argument against this rationale ?

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Here
is an excellent argument given by Galileo in favor of the rotation of
the Earth and why things would still fall to the same place even if the
Earth were rotating:

In replying to this, those who make the earth movable answer that the canon and the ball which are on the earth share its motion or rather that all of them together have the same motion naturally.

Therefore the ball does not start from rest at all but to its motion about the center joins one of projection upward which neither removes not impedes the former.

You
will see the same thing by making the experiment on a ship with a ball
thrown perpendicularly upward from a catapult. It will return to the
same place whether the ship is moving or standing still

The profundity of this argument is that, the very same principle that ‘ball does not start from rest at all  but with velocity of the earth’ is used by space shuttles to reach orbital velocity with lesser fuel consumption.

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But despite Galileo’s argument, it was still believed for a long time that it were the heavens that moved and not the earth.

For
God hath established the world which shall not be moved in spite of
contrary reasons because they are clearly not conclusive persuasions.

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