6th April, 2020
Far Side of the Moon
Due to the tidal locking of the moon, we view the same, near side of the moon at any given time. The far side of the moon is strikingly different. Note the absence of maria - the large grey cooled seas of lava. Dotted with craters of nearly every size, this side of the moon seems to have been battered far worse than the near side. This image was captured by NASA's Lunar Reconnaissance Orbiter
Image source: https://moon.nasa.gov/
15th April, 2020
Quasar 3C 279
Last April, the Event Horizon Telescope's image of the black hole in the radio galaxy M87 marked the start of a new era of imaging in astronomy. This April, we focus on the EHT's observation of the quasar 3C 279. This is a supermassive black hole, commonly referred to as a blazar. The jets launched by this quasar are aligned such that they point towards the Earth. Consequently, dramatic fluctuations in brightness can be observed and this corresponds to high temperature, bright, and energetic emissions.
The puzzling observation here is that there are two structures, instead of the expected single structure. Each of these structures are moving at nearly the speed of light. As the two structures are not aligned, scientists hypothesize that this indicates a bending of jets.
Image source: https://public.nrao.edu/
More info : https://insidetheperimeter.ca
August, 2020
Comet NEOWISE
Amidst the pandemic, the night sky has a rare treat to offer - a comet sighting. Comet NEOWISE was discovered earlier this year by the asteroid-hunting after-life of the Wide-field Infrared Survey Explorer( WISE), NEOWISE. Comets are icy space-balls which heat up as they approach the sun. This approach is accompanied by the comet developing two tails. One is simply a tail of gas and dust disintegrating from the body whereas the other one is an' 'ion tail' made of electrically-charged gas ions. At 5km in diameter, Comet NEOWISE is hurling through the Solar System at a whopping 231,000 kph with about 13 million Olympic swimming pools worth of water - typical for a usual comet which is about half dust, half water.
Comet NEOWISE is bright enough to be visible to the naked eye after sundown in the Northern Hemisphere, close below the Big Dipper (the large bear) constellation. It appears as a fuzzy star with a tail and is best visible away from city lights. With a pair of regular binoculars, the tail will be easily visible.
February 2021
2020 SO
Last September, Earth's local celestial family re-welcomed an estranged member - a temporary satellite, or minimoon, called 2020 SO. The story dates back to the 1960s. In 1966, NASA launched its second lunar lander in the unmanned Surveyor program, Surveyor 2. Part of its mission was to collect data on the lunar environment in preparation for the Apollo missions.
Surveyor 2 was launched on a Centaur rocket booster and NASA data suggests that this newly captured object, is none other than this very rocket booster. 2020 SO has had quite a space journey since its launch in the 1960s and verifying its identity is a remarkable scientific feat (Read more here). The team led by Vishnu Reddy, planetary scientist and associate professor at the Lunar and Planetary Laboratory in Arizona, USA analyzed the spectra reflected off of 2020 SO and compared its composition to the material that Centaur rocket boosters were made from.
The image on the left shows the path of 2020 SO in its journey. As of today, 2020 SO will make one last approach to Earth within a week after which it will forever disappear into outer space. Image Source: NASA/JPL
April 2021
Rosette Nebula
It would take all of one's will-power to not be enchanted by the beauty of this nebula. The Rosette nebula is perhaps my favourite nebula of all. This bustling nebula is home to countless newborn stars and is teeming with young and hot stars. Its eye-catching symmetrical shape is a result of winds and radiation from these stars. A curious point is the apparent 'hole' in the centre of the nebula. This feature is common in nebulae with massive stars located at the centre of the nebula, which blast out matter and radiation creating a cavity in the process. Given the age and mass of the central stars of this nebula, astronomers would ideally expect a much larger hole than the one imaged. Why is the hole significantly smaller then?
Astronomers at the University of Leeds and Keele University may have an explanation, with the aid of computer simulations. If the Rosette nebula is shaped like a thin disk rather than a sphere or thick disk, the dynamics of the evolving nebula may explain the divergence of the stellar winds away from the centre of the nebula. Read more about their work here.
Image source: NASA
August 2021
Perseid Meteor Shower
Image Source: Space.com, Tyler Leavitt
When I look up to the skies, it is inevitable for my mind to wander off into a physics dreamland. Thinking about the dusty bands of the Milky Way, the nebulae, the stars and the celestial bodies and how they formed, or what they would evolve into, is something quite enticing - much like midnight flirtations with the stars. But sometimes, the simplest and most easily overlooked sights are the most splendid - such as meteor showers.
April 2022
Mercury Transit
Image Source: NASA's Goddard Space Flight Centre
Our familiar Moon isn't the only celestial body which we get to witness when in eclipse. When planets pass in front of their host stars, as viewed from the Earth, the amount of light we receive from the star diminishes. When hunting for exoplanets, it is this very signature that allows astronomers to detect them. In this image, we see Mercury transiting in front of the sun, in the very same way exoplanets occult their host stars. By studying the duration, depth and wavelength changes of the transit, astronomers can deduce properties such as the exoplanet's mass, radius and atmospheric contents. This is known as the transit method for detecting exoplanets, and about 4000 planets have been detected using this method.
May 2022
Protoplanetary Disk
Image Source: By ALMA, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=36643860
A highlight of my BSc. degree is the module I recently completed, Exoplanets, taught by Prof. Amaury Triaud who is also the co-discover of the famed Trappist-1 System. Exoplanets are planets which orbit stars other than the sun, and offer crucial insights into how planetary systems evolve, and may even answer some questions on how our planet formed. Protoplanetary discs are discs of gas, dust and chunks of rock surrounding the new-born star. When a massive body clears out a path, or accretes matter in its sphere of influence, a planet is born. Imaging such systems provide insights into the different methods for forming different planets. They also explain the changing orbits of planets, and exoplanetologists can also calculate the probability of planets being ejected from the system. There's a very slight chances that in several million to billion years, Venus may be ejected from our Solar System! This image of the HL Tau protoplanetary disc gives a glimpse into the rare treat that is the birth of a planet. Enjoy! (And should you have any questions, please do not hesitate to reach out using the form in the About page, or the 'Ask a Physicist' feature on this page)
July 2023
Odd Radio Circles
Image : ORC1; MeerKAT Telescope, Dark Energy Survey 2022
Over the course of the past year, I delved into radio astronomy and machine learning for my masters dissertation. One class of objects I encountered during my research which caught my eye due to its stunningly simple appearance but equally shocking lack of scientific literature, were Odd Radio Circles (ORCs). Despite the visual similarity to planetary nebulae, ORCs have a fundamental difference from them. They cannot be observed at visual wavelengths. In fact, they only emit in the radio spectrum - the key reason for scientific intrigue. The following excerpt from my dissertation summarises the potential physics behind this fascinating object:
Compared to other radio objects, ORCs are relatively novel and poorly understood. These objects are faint, diffuse circular objects of radio emission with no emission at non-radio wavelengths. ORCs surround galaxies at moderate redshifts from 0.2 – 0.6, and some ORCs are known to have central galaxies. The circular structure may arise due to a spherical shockwave form the central galaxy due to a cataclysmic event such as a supermassive blackhole merger. Alternatively, it may appear to have a circular shape as it may be a double-lobed radio AGN viewed end-on. Lastly, the ORC may be a result of intergalactic interactions. A further ambitious theory hypothesises that ORCs may be the throat of the theoretically predicted wormholes
December 2023
Supernova Remnant
Image : Supernova remnant SNR G359.1-0.52 , 'The Mouse', and 'The Snake'; Credit: SARAO
The Universe in radio wavelengths is remarkable treat to the eye. This image is a snippet of the MeerKAT Galactic Plane Survey, and shows the supernova remnant, SNR G359.1-0.52. The elongated feature on the left of the bubble-like remnant is a prominent feature called 'the Mouse'. This is a runaway pulsar, the remnant pulsar star which was likely ejected during the supernova explosion. This star, also known as a rotating neutron star, leaves a trailing radio jet, as is seen.The pulsar is centred at the centre of the bright red blob. To the right, is 'the Snake'. This is a radio filament - a region emitting strongly in radio frequencies, due to charged particles moving at speeds close to the speed of light, in a magnetic field. As these particles approach the centre of the Milky Way galaxy, they spiral around the centre, creating the distinct, smooth elongated feature we see in this image.
Read more about how MeerKAT and its results are changing the way we see the Universe, here.