Latest news with #IndianInstituteofAstrophysics
Deccan Herald
23-04-2025
- Science
- Deccan Herald
Bengaluru to experience Zero Shadow Day today
Bengaluru: Bengaluru will experience Zero Shadow Day on Thursday at exactly 12.17 pm. Objects will cast a shadow exactly downward, causing objects on the ground to have no visible to astronomers at the Indian Institute of Astrophysics, Bengaluru (IIA), this phenomenon occurs twice a year, once around April 24 or 25 and a second time around August local noon, the sun will be at its zenith (highest point in the sky), but this highest point is not exactly overhead on most days. The sun transits north or south of it due to the 23.5-degree tilt of the Earth's axis of rotation with respect to the plane of Earth's revolution around the sun. On Zero Shadow Days, however, the sun is directly overhead, causing vertical objects to cast no visible the sun transits directly above the Tropic of Cancer (+23.5° latitude), it is called the summer solstice (around June 21), and when the sun transits directly above the Tropic of Capricorn (-23.5° latitude), it is called the winter solstice (around December 22)..World Psycho-Oncology Day: Experts demand psychosocial care for cancer patients .The sun transits across the equator twice a year on days called equinoxes. The arc made by the sun in the sky changes throughout the year. The arc moves southwards starting on the summer solstice and passes over the equator around September 23 (autumnal equinox), subsequently transiting directly over the Tropic of Capricorn during the winter solstice. After this, the arc makes its journey northward. The arc's transit between one tropic and the other takes six for people who live in the tropics (+23.5° to -23.5° latitude), the sun passes directly overhead twice a year — once when the arc transits northward and once when the arc transits Shadow Days occur on different days for different cities when the sun transits directly overhead based on their planned at 10 activities: 11.30 session: 12.30 is coordinating with a team in Bhopal to compute the diameter of the Earth through shadow length measurement.
The Hindu
23-04-2025
- Science
- The Hindu
IIA study sheds light on curious case of missing dark matter in a distant galaxy
Astronomers at the Indian Institute of Astrophysics (IIA) have found the reason for the strange deficiency of dark matter in the distant galaxy NGC 1052-DF2. Dark matter is a critical component of galaxy formation. According to the Department of Science and Technology, earlier models have shown that the Ultra-diffuse galaxy (UDG) NGC 1052-DF2 is deficient in dark matter, which conflicts with the standard galaxy formation and evolution models. It said that previous studies of NGC 1052-DF2 predict a total 'dynamical mass' within the spatial extent of the galaxy to be less than 340 million solar masses, which is comparable to the estimated mass of the stars of 200 million solar masses. 'This surprising result implies that within the observed extent of the galaxy, the mass is mostly composed of primarily stars that we are familiar with, and that dark matter is significantly less than expected as compared to spiral galaxies like the Milky Way. This contradicts the established paradigm about dark matter, which is needed to explain hierarchical structure formation in the Universe,' the department said. 'We find that NGC 1052-DF2 poses interesting questions regarding the formation of galaxies with minimal dark matter content, the astrophysical processes regulating the formation of such galaxies, as well as the potential nature of dark matter itself,' said astronomer K. Aditya, whose research was published in the journal Astronomy & Astrophysics. To shed light on this problem and to resolve the discrepancies in the mass estimation of NGC 1052-DF2, Mr. Aditya constructed models using the stellar density as an input parameter and constrained the parameters corresponding to the dark matter halo. He then used the observed stellar velocity dispersion profile as a constraint on the model. 'We find that mass models with a 'cuspy' (higher density in the central regions) dark matter halo are comparable to models with no dark matter. Moreover, these cuspy dark matter halo fails to consistently account for the observed velocity dispersion in the inner and outer regions of the galaxy. Consequently, we rule out the possibility of a cuspy dark matter halo for describing the mass models of NGC 1052 - DF2,' said Aditya.
The Hindu
22-04-2025
- Science
- The Hindu
Triple conjunction of Venus, Saturn and Moon on April 25
A rare celestial event would be visible over the Bengaluru skies in the early hours of April 25. There would be a triple conjunction of the planets Venus and Saturn, along with the crescent Moon. According to astronomers, a glimpse of this phenomenon can be viewed at around 5.30 am on April 25. 'The morning sky on April 25 will present a beautiful spectacle about an hour before sunrise. Look east and find a bright Venus close to a crescent Moon with a feeble Saturn a couple of degrees below the latter,' said Prof. R.C. Kapoor, formerly with the Indian Institute of Astrophysics (IIA). The formation of the three celestial bodies will resemble a smiley face. However, this may not be visible in India, said Prof. Kapoor. 'On the morning of 25 April next, Moon, Venus, and Saturn will come together to form a smile configuration. But in India, we will see them close, but the trio will still be hours away from the celestial smile. That is, India will miss the particular moment. Smile-y or no smile-y, the sight nearer home will still be a beautiful one from wherever you watch. A small telescope will add to the thrill. Saturn may disappoint a bit as its rings at present are nearly edge-on,' Prof. Kapoor said. Though this event can be seen with the naked eye, Prof Kapoor cautions not to view the sun directly or with a telescope.
Time of India
22-04-2025
- Science
- Time of India
Bengaluru to witness ‘Zero Shadow Day' on April 24; here's the science behind the phenomenon
Zero Shadow Day is a truly intriguing astrophysical phenomenon and a one-off chance to watch the sun and Earth interact with each other head-on. When the sun remains directly above during noon, vertically standing objects stop casting visible shadow for a second or so. This phenomenon exists because the sunlight strikes in precisely a 90-degree angle such that the shadow points straight downwards, practically putting objects out of sight. The phenomenon is easily seen in the areas between the Equator and the Tropic of Cancer, such as in Indian cities such as Bengaluru, Chennai, and Mangaluru. Discover the science behind this phenomenon and everything you need to know about. Bengaluru set to experience Zero Shadow Day: Date and time Bengaluru, often referred to as the Silicon Valley of India, is poised to experience a Zero Shadow Day at approximately 12:17 pm on April 24. According to scientists from the Indian Institute of Astrophysics (IIA), during this rare event, the sun will be directly overhead, resulting in vertical objects casting no shadow whatsoever. What is Zero Shadow Day by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like Trade Bitcoin & Ethereum – No Wallet Needed! IC Markets Start Now Undo Zero Shadow Day is the day when the sun is directly overhead, or the place in the sky exactly above a particular place. When this occurs, the rays of the sun hit the Earth at right angles, and vertical structures such as trees, poles, and buildings never cast a shadow. Instead of the slanting shadows we're accustomed to in daylight, everything that stands upright will have its shadow below it, essentially beyond the eye of man. The effect will take place within a brief time period around noon when the sun is overhead, at its highest point in the sky. Throughout the remainder of the day, shadows will be as usual because Earth continues to rotate. The Earth is tilted approximately 23.5 degrees on its axis and thus the sun does not travel in a straight line across the sky throughout the year. The reason is that, because the Earth is tilted, the sun is never directly overhead at any location on the planet. However, in regions between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S), there are certain months of the year when the sun will be directly overhead at noon. Science behind Zero Shadow Day phenomenon According to Dr. Niruj Mohan Ramanujam, the director of Indian Institute of Astrophysics' Science Communication, Public Outreach, and Education (SCOPE) division the phenomenon repeats itself twice a year in cities like Bengaluru and follows the path of the sun in the sky. The sun's rays are vertical and strike the Earth during noon when the sun is highest on the horizon of the day. This coincidence with the zenith only takes place between latitudes in the Equator and the Tropic of Cancer. The sun is not directly over more northerly or southern cities, so Zero Shadow Day is a single occurrence for specific latitudes. Cities that experience Zero Shadow Day This is a phenomenon that is not limited only to Bengaluru, India. It is common to every city located between the Equator and the Tropic of Cancer (23.5°N latitude). These cities have direct sunlight at some time of the year, and because of this, the phenomenon of Zero Shadow Day is experienced. Bengaluru: Zero Shadow Day is celebrated twice a year, first on April 24 or April 25 and then on August 18. The date is slightly off every year based on the physics of Earth's orbit. Chennai: Chennai also experiences the same phenomenon since it lies at a lower latitude where the phenomenon is even more pronounced. Mangaluru: Even this sea-level city gets to experience the phenomenon of Zero Shadow Day since it falls between the Equator and the Tropic of Cancer. Such cities fall on those latitudes that have the Sun directly overhead solar zenith and hence Zero Shadow Day is a routine phenomenon. Timing of Zero Shadow Day Zero Shadow Day occurs on a date calculated based on the Earth's orbit and the tilt of its axis. As the Earth orbits around the sun, different regions of the world get direct sunlight at different times of the year. Zero Shadow Day, for instance, occurs twice a year in Bengaluru, in April and August. The date and time slightly differ from year to year but generally around noon. Zero Shadow Day significance Zero Shadow Day offers a bigger optical event; it offers the chance to witness the way the Earth's axis tilt and orbit determine how sunlight dances upon the Earth. To those privileged to observe it, the effect is reminiscent of heavenly forces that govern the life of the Earth. It also provides excellent opportunities for science education and outreach because individuals can easily visualize the impact of the Earth's movement. Zero Shadow Day can be a good source to teach students about events such as the rotation of the Earth, sun path along the sky, and the process by which the latitude controls the amount and direction of light. It is a physical occurrence of the Earth's tilt and orbit causing various phenomena such as the day duration and seasons. Also Read | Indian astronaut Shubhanshu Shukla to study tardigrades, space farming, and other key experiments during Axiom-4 mission in May
Time of India
22-04-2025
- Science
- Time of India
Zero shadow day in Bengaluru on April 24; step outside at 12.17pm and see the sun do magic
BENGALURU: Bengaluru will experience the ' zero shadow ' phenomenon at exactly 12.17pm on April 24, when the sun is directly overhead, according to scientists at the Indian Institute of Astrophysics (IIA). Niruj Mohan Ramanujam, Head of IIA's Science Communication, Public Outreach, and Education (SCOPE) section, explained that during this event, the sun reaches its zenith, causing vertical objects to cast no visible shadows as they fall directly beneath them. All locations in India situated below the Tropic of Cancer—including Bengaluru, Chennai, and Mangaluru—experience Zero Shadow Day , according to Ramanujam. In Bengaluru, this phenomenon occurs typically around April 24–25 and again on August 18, he stated. Zero Shadow Day will reach the Tropic of Cancer on June 21, the summer solstice and the end of Uttarayana—the sun's northward journey in the Hindu calendar, Ramanujam added.
