Posts Tagged 'Astronomy'

A New Window on the World

The motto of the Pythagoreans was “All is Number” and Pythagoras may have been the first person to imagine that the workings of the world might be understood in mathematical terms. This idea has now brought us to the point where, at a fundamental level, mathematics is the primary means of describing the physical world. Galileo put it this way: the book of nature is written in the language of mathematics [TM102, or search for “thatsmaths” at irishtimes.com].

gravitational-waves-3d

Visualization of gravitational waves. Image credit MPI/Gravitational Physics/ITP Frankfurt/ZI Berlin.

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Kepler’s Magnificent Mysterium Cosmographicum

 

Johannes Kepler’s amazing book, Mysterium Cosmographicum, was published in 1596. Kepler’s central idea was that the distance relationships between the six planets (only six were known at that time) could be represented by six spheres separated by the five Platonic solids. For each of these regular polyhedra, there is an inner and an outer sphere. The inner sphere is tangent to the centre of each face and the outer sphere contains all the vertices of the polyhedron.

kepler-orbits

Figure generated using Mathematica Demonstration [2].

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The Search is on for Planet Nine

Then felt I like some watcher of the skies
When a new planet swims into his ken.

John Keats: On First Looking into Chapman’s Homer

Pluto, discovered in 1930, orbits in the Kuiper Belt, a ring of asteroids and icy debris beyond Neptune. About ten years ago, it was reclassified as a “dwarf planet”, so now we have eight planets. Is there a ninth anywhere? A recent paper in the Astronomical Journal presents evidence of a large planet in an orbit far beyond Neptune. If confirmed, this would be a dramatic confirmation of our understanding of solar system dynamics [TM088, or search for “thatsmaths” at irishtimes.com].

Planet-Nine-Orbit-Plots

Orbits of six trans-Neptunian objects aligned in one direction, suggesting a perturbing body, Planet Nine (?). Caltech/Robert Hurt.

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Thomas Harriot: Mathematician, Astronomer and Navigator

Sir Walter Raleigh, adventurer, explorer and privateer, was among most colourful characters of Tudor times. He acquired extensive estates in Waterford and Cork, including Molana Abbey near Youghal, which he gave to his friend and advisor, the brilliant mathematician and astronomer Thomas Harriot.

Thomas Harriot (1560 - 1621)

Left: Sir Walter Raleigh (1552-1618). Right: Thomas Harriot (1560?-1621)

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The Great American Eclipse

Just two years from now, on Monday, August 21, 2017, the Moon’s shadow will sweep across the United States at a speed of over 2,000 km/hr. The Great American Eclipse of 2017 will generate a frenzy of activity. [TM074: search for “thatsmaths” at irishtimes.com ].

Moon between NASA’s Solar Dynamics Observatory and the Sun, giving a partial solar eclipse from space on Jan. 30, 2014. Image NASA.

Moon between NASA’s Solar Dynamics Observatory and the Sun,
giving a partial solar eclipse from space on Jan. 30, 2014. Image NASA.

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Pluto’s Unruly Family

An astrodynamical miracle is happening in the sky above. Our ability to launch a space-probe from the revolving Earth to reach a moving target billions of kilometres away almost ten years later with pinpoint accuracy is truly astounding. “New Horizons” promises to enhance our knowledge of the solar system and it may help us to understand our own planet too.

Four tiny moons (on left) orbit the binary system of Pluto (top right) and Charon.

Four tiny moons (on left) orbit the binary system of Pluto (top centre right) and Charon [Image NASA]

[See this week’s That’s Maths column (TM071): search for “thatsmaths” at irishtimes.com].

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The Hodograph

The Hodograph is a vector diagram showing how velocity changes with position or time. It was made popular by William Rowan Hamilton who, in 1847, gave an account of it in the Proceedings of the Royal Irish Academy. Hodographs are valuable in fluid dynamics, astronomy and meteorology.

Hodograph plot of wind vectors at five heights in the troposphere. This indicates vertical wind shear and also horizontal temperature gradients. Since the wind veers with height between V2 and V3, it is blowing warmer air north-eastwards to a colder region (image source: NOAA).

Hodograph plot of wind vectors at five heights in the troposphere. This indicates vertical wind shear and also horizontal temperature gradients. Since the wind veers with height between V2 and V3, it is blowing warmer air north-eastwards to a colder region (image source: NOAA).

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