Category Archives: Science

Measuring the Earth’s waist on the longest summer day !

The importance of June 21 might have gone unnoticed by the layman, but for the students of various Delhi schools, it was a big chance to emulate the Greek astronomer Eratosthenes. These students participated in an exercise on Thursday to measure the earth’s circumference on the longest day of summer.
Organised by Science Popularisation of Communicators and Educators (SPACE), the participants took actual measurements of the shadows made by the sun to measure the circumference of the earth as done 2,300 years ago by Greek astronomer Eratosthenes. Eratosthenes was the first person to calculate the circumference of the earth by using a measuring system using stades or the length of stadiums during that time period (with remarkable accuracy).
Thursday being the longest day and the shortest night, we measured the circumference of the earth. After today the duration of the day will be shorter and of the night will be of longer,” said Pooja Kumar of SPACE.
“We are observing the angle of the sun and measuring the shadows. In general, the exact timing of the summer solstice changes from year to year,” she added.
Known as the Project Paridhi ( the word paridhi means “measure “ making it quite apt for the Eratosthenes experiment), the measurement activity went on from 9:30 in the morning to 2 pm at the Jantar Mantar. The project involves participants taking measurement of shadows at noon, at different places on the same longitude, such as Delhi and Bangalore.
“I am measuring the shadow of the sun through an instrument called gnomon meaning ‘indicator’. It is the oldest method to measure direction, time and location by shadows,” said Mehul, a student from Ryan International, Rohini.
“Using the shadow of the sun we will find out the angle of the sun. We are measuring the shadow after every 5 minutes,” Mehul added.
SPACE also partnered with astronomers from Kazakhistan for the conduct of this experiment.
What we have gathered is that Thursday would be 14-hour long day. We measured the sun’s shadow every 5 minutes and we will calculate the earths circumference by the formula known,” said Vibhu Narayan, a student of St. Columba’s school in Delhi.

Eyes turn skyward as Venus travels across sun

From the U.S. to South Korea, people around the world turned their attention to the daytime sky on Tuesday and early Wednesday in Asia to make sure they caught the once-in-a-lifetime sight of the transit of Venus.

For some astronomers, it wasn’t just a rare planetary spectacle as it won’t be seen for another 105 years. They hoped the passage of Venus between the Earth and the sun would spark curiosity about the universe and our place in it.

Sul Ah Chim, a researcher at the Korea Astronomy and Space Science Institute in South Korea, said he hoped people see life from a larger perspective, and “not get caught up in their small, everyday problems.”

“When you think about it from the context of the universe, 105 years is a very short period of time and the Earth is only a small, pale blue spot,” he said.

While astronomers used the latest technology to document the transit, American astronaut Don Pettit aboard the International Space Station was planning to take photos of the event and post them online.

In Mexico, at least 100 people lined up two hours early to view the event through telescopes or one of the 150 special viewing glasses on hand, officials said. Observation points were also set up at a dozen locations.

Venus, which is extremely hot, is one of Earth’s two neighbours and is so close in size to our planet that scientists at times call them near-twins. During the transit, it will appear as a small dot.

The transit is happening during a 6-hour, 40-minute span that began just after 2200 GMT. What you can see and for how long depends on what the sun’s doing in your region during that exact window, and the weather.

Those in most areas of North and Central America will see the start of the transit until the sun sets, while those in western Asia, the eastern half of Africa and most of Europe will catch the transit’s end once the sun comes up.

In Hawaii, astronomers planned viewings at Waikiki Beach, Pearl Harbor and Ko Olina. At Waikiki, officials planned to show webcasts as seen from telescopes from volcanoes Mauna Kea on the Big Island and Haleakala on Maui.

NASA planned a watch party at its Goddard Visitor Centre in Maryland with solar telescopes, “Hubble-quality” images from its Solar Dynamics Observatory Mission and expert commentary and presentations.

Experts from Hong Kong’s Space Museum and local astronomical groups were organising a viewing on Wednesday outside the museum’s building on the Kowloon waterfront overlooking the southern Chinese city’s famed Victoria Harbour.

This will be the seventh transit visible since German astronomer Johannes Kepler first predicted the phenomenon in the 17th century. Because of the shape and speed of Venus’ orbit around the sun and its relationship to Earth’s annual trip, transits occur in pairs separated by more than a century.

It’s nowhere near as dramatic and awe-inspiring as a total solar eclipse, which sweeps a shadow across the Earth, but there will be six more of those this decade.

International Spill overs and Water Quality in Rivers: Do Countries Free Ride?

Spill over problem is a big issue for the whole world because due to this the quality of water decreases and causes a lot of problems. Spill over causes the environmental issues, climate change, ozone depletion and acid rains. A lot of research has been done on environmental issues by the whole world to resolve it but few of them are in practice. Statistical analysis also made from the river and environmental data. The data given by GEMS for the 49 countries describes the difference between domestic observations (68%) and international observations (32%).

The river water quality is also affected by human population. We see that a lot of causes the water quality degradation in rivers. International rivers flow more than the domestic rivers because of pollutant concentration. This data has been verified from the GEMS river flow data and temperature. The effect of spill overs on pollution can be determined using statistics equations including the factors like upstream pollution, GDP per capita etc. While doing statistical analysis it shows some errors in estimation because of differences in monitoring frequencies. The effect varies from one country to another as variability in data for domestic and international stations.

The pollution level at the upstream boarder’s stations is 42% higher than the other stations. Statistically determined point estimates on downstream are lower than the upper stream. Statistical analysis sometime is difficult because it includes countries effect which varies frequently. The countries where there are shared rivers the free riding national pollution level will be higher as compared to others. External borders to the EU, upstream stations have higher up to 111% more pollution level than others. In EU stations according to statistical analysis the free riding is less than non-EU upstream stations. There are some more factors which also affects the cost and benefits of water quality. The population in upstream stations have significantly positive coefficient as illustrated in the report. Including country effect in upstream population the elasticity is 0.007.

Rate of flow of river enters with negative coefficient which is consistent with dilution. In upper stream the deoxygenating rate, denoted by ‘k’ has significantly positive point estimate which is inconsistent to lower stream. But if you introduce country effect while analysing the spill over and water quality in rivers, the obtained time trend is significantly positive. The empirical analysis analyse that the international spill overs impair water quality in rivers. Pollution in the stations outside of EU has higher than the other stations. This report suggests that there is nothing any kind of collaboration among the countries regarding this kind of spill over problem and sharing the rivers to the boarders.

Overall it suggests that if there is no river sharing among the countries and also if there is no proper environment situations available to handle this kind of spill over problems it is very difficult to overcome this problem.