Description

Source: Hindu

Disclaimer: Copyright infringement not intended.

Context

The Vikram Sarabhai Space Centre (VSSC) in Thiruvananthapuram has unveiled an innovative polar sundial at its Space Museum’s ‘Rocket Garden.’

Details

The sundial combines advanced design with scientific precision to provide Indian Standard Time (IST) and the date.

It features a 3D-printed miniature of the Rohini series RH200 sounding rocket serving as the upright element (style) casting the shadow.

Features of the Polar Sundial

Accurate IST Display:

Unlike traditional sundials which show only the local solar time, this sundial integrates analemmatic correction and longitude adjustments to display IST.

Unique Analemmatic Correction:

The hour lines are replaced with inverted analemma curves enabling precise time conversion.

The analemma is the figure-eight pattern traced by the Sun in the sky over a year due to the Earth’s axial tilt and elliptical orbit.

Polar Configuration:

The sundial plate is aligned parallel to the Earth’s polar axis.

The angle of the wedge-shaped structure holding the sundial is calibrated to Thiruvananthapuram’s latitude.

Integration of Space Themes:

The Rohini RH200 miniature represents India’s pioneering efforts in rocket science.

Aligns with ISRO’s legacy and innovations.

About Sundial

It is a timekeeping instrument that uses the position of the Sun's shadow cast by a gnomon (a rod or triangular blade) to indicate the time of day. It is one of the earliest devices for measuring time reflecting humanity's ingenuity in understanding celestial movements. Sundials embody a fascinating blend of science, art and history.

History of Sundials

Origins:

The earliest sundials date back to 3500 BCE in ancient Egypt where obelisks functioned as simple sundials.

Ancient Babylonian and Chinese civilizations also used similar shadow-based devices for timekeeping.

Classical Era:

The Greeks and Romans refined sundials into portable and sophisticated instruments.

The Roman engineer Vitruvius described numerous designs in his writings.

Medieval Period:

Islamic scholars introduced innovations, such as accurate mathematical calculations to improve sundial precision.

Sundials were widely used in European monasteries to regulate prayer times.

Modern Relevance:

While obsolete for practical timekeeping, sundials remain popular as decorative garden features and educational tools.

Components of a Sundial

Gnomon:

The rod or triangular blade that casts the shadow.

Typically aligned with Earth's axis for accuracy.

Dial Plate:

The flat surface on which hour lines are marked.

May be circular, horizontal or vertical depending on the sundial's design.

Hour Lines:

Markings that divide the dial into hours or other time intervals.

These lines vary in spacing due to the Sun's apparent motion.

Types of Sundials

Horizontal Sundials:

The dial plate is flat and placed horizontally.

Commonly used in gardens and outdoor spaces.

Vertical Sundials:

Mounted on walls with a vertical dial plate.

Popular in architectural designs.

Equatorial Sundials:

The dial plate is aligned parallel to the equatorial plane.

The gnomon points directly at the celestial poles.

Polar Sundials:

The dial plate is parallel to Earth's axis and the hour lines are evenly spaced.

Analemmatic Sundials:

Elliptical in shape with a movable gnomon for seasonal adjustments.

Portable Sundials:

Small, handheld designs used historically for travel.

How Sundials Work

Principle:

Sundials work on the concept of Earth's rotation which causes the Sun to appear to move across the sky.

Mechanism:

The Sun's rays cast a shadow from the gnomon onto the dial plate.

The position of the shadow corresponds to specific hour markings.

Factors Affecting Accuracy:

Alignment of the gnomon with Earth's rotational axis.

Latitude of the location.

Seasonal changes in the Sun's position.

Advantages and Limitations

Advantages	Limitations
Simple, non-mechanical timekeeping.	Cannot function without sunlight.
Eco-friendly and durable.	Affected by weather conditions (e.g., clouds).
Culturally and historically significant.	Requires proper alignment and calibration.

Rohini RH-200

It is a prominent sounding rocket developed by the Indian Space Research Organisation (ISRO) for atmospheric research and meteorological studies.

Attribute	Details
First Launch	1979
Total Launches	Over 1,600.
Consecutive Successes	200th consecutive successful launch achieved on November 23, 2022.
Stages	Two-stage, both powered by solid motors.
Payload Capacity	Up to 10 kilograms.
Apogee (Maximum Altitude)	Approximately 80 kilometers.
Applications	Meteorological data collection Atmospheric studies Space physics research Technology demonstration Educational and student experiments
Achievements	Integral to ISRO's early space endeavors. Supported over 1,600 missions. Achieved 200 consecutive successful launches by November 2022 Utilized for the first student payload launch in India by VIT University.

About VSSC

It is a major space research centre of the Indian Space Research Organisation (ISRO) focusing on rocket and space vehicles for India's satellite programme. It is located in Thiruvananthapuram.

The centre had its beginnings as the Thumba Equatorial Rocket Launching Station (TERLS) in 1962. It was renamed in honour of Vikram Sarabhai, often regarded as the father of the Indian space program. H.G.S. Murthy was appointed as the first director of Thumba Equatorial Rocket Launching Station.

Sources:

Hindu

PRACTICE QUESTION

Q.Consider the following statements regarding the Rohini RH-200 sounding rocket:

1. It is a single-stage rocket used primarily for launching satellites.
2. The RH-200 achieved its 200th consecutive successful flight in 2022.
3. It is used for atmospheric studies and meteorological data collection.

Which of the above statements is/are correct?

(a) 1 and 2 only

(b) 2 and 3 only

(d) 3 only

Answer: (b)

Explanation:

Statement 1 is incorrect. The RH-200 is a two-stage rocket and is not used for launching satellites. It is a sounding rocket designed for atmospheric research.

Statement 2 is correct. The 200th consecutive successful launch of the RH-200 was achieved in November 2022.

Statement 3 is correct. The primary purpose of the RH-200 is atmospheric studies and meteorological data collection making it an integral part of ISRO’s scientific exploration.