The Sun and Heat

¹ A mathematician’s job is to write annual forecasts.

I will do this in next year, 1602, as my duty as philosopher-mathematician.

More and more people are interested in forecasts. That is why I forecast with certainty that there will be plenty of forecasts this year from the many new authors that make forecasts day by day.

² Those forecasts will be either be proven by events, or be disproven as futile and useless. Usually, the latter will be remembered the most.

³ Like cause, like outcome.

In their forecasts, astrologers admit that the causes are partly physical, partly political, but mostly uncertain, sometimes obscure and very incomplete. Very often the cause cannot be defined at all.

When astrologers upon basis of such a unfathomable causes do succeed to tell the truth, this should be considered a luck; nevertheless, commonly and much more often it is seen as a matter of some higher and mystic impulse.

⁴ Many things exist naturally, while the causes are unknown.

• Some causes are known by all
• Other causes are understood by only a few or even no one

⁵ The most common, powerful and certain cause known by everyone is the approaching and withdrawal of the Sun.

This refers to winter solstice, i.e. 21.12.1601 shortly prior 6 PM, and to summer solstice, i.e. 21.6.1602 at 10:30 PM.

The former brings about the cold of winter to northern latitudes, the latter – the heat of summer.

⁶ The nature of this cause results from inclination of ecliptics. Prague, Bohemia, latitude 50°05´45´´.

The inclination of the ecliptics in this century makes 23°31´30´´, as discovered by the greatest of astronomers, Tycho Brahe, whom we have recently lost.

Thus, in winter we find the Sun, our generator of heat, only 7 hours and 49 minutes above the horizon. It warms up our air just for a short time.

And then, completely hidden below the horizon twice as long, it does not heat at all.

And in summer, on the contrary, the Sun stays above 16 hours and 22 minutes, and it heats.

It hides its activity for the period shorter than a half of this time span.

Tycho Brahe de Knudstrup (Tyge Otessen Brahe, December 14, 1546, Knudstrup, Danemark – October 24, 1601, Prague).

⁷ Air, just like water and earth (as far as elements are considered), except when those are warmed for a long time, turn immediately to their nature (natural disposition) and they cool down.

The well-known statement of Aristotle – that the nature of air itself is warm – will probably be false.

Aristotle says that the nature of the air-element in terms of quality is warm and wet.

⁸ The nature of everything connected with substance is cold. And whatever is potentially warm, takes its nature from the life force, be it added or generated.

⁹ There is another and much more important reason why the Sun, when it is high above, gives more heat then when it is low: it is because the sun rays, when the Sun is low, fall upon our Earth sidelong and weak, whereas when the Sun is high, the rays fall upon Earth much more intensely, being almost perpendicular to it.

Nowadays, no one can explain why the non-substantial sun rays act in the same way as the substantial and dense bodies falling upon one another this way.

¹⁰ The Sun in summer passes over Prague almost 4 times higher than in winter.

This, like above stated, implies that during the shortest day, there is no more than 1/8 of the warmth which falls upon the nature elements during the longest summer day.

¹¹ Regarding that one eighth of warmth in winter, it does not even take effect as a whole, because the Sun rises only a little above the horizon in winter, and moreover, it stands much more sidelong towards the layer of atmosphere.

Suppose that the dividing line of pure air, where the sun rays bend, is located about one german mile (ca. 7,5 km) of perpendicular distance from us (it hardly could be more because in fact the altitude of the air, which causes sunset or sunrise, differs from that one in which the rays of the stars bend).

Therefore, the thickness of air which lays between the Sun and Earth is 1 and one ninth of german mile in summer, and 3 and 1/3 of german mile in winter.

This is why the sun’s ray is 3 times weaker in winter.

If we take into consideration those three causes together, then in winter there is only 1/24 of summer warmth remaining.

¹² Notwithstanding those 3 causes are most obvious in days of winter and summer solstice, the cold does not necessarily have to be at its maximum in the former case, nor the heat in the latter.

In fact, there is another cause which makes the winter cold the most intense at the beginning of February and the summer heat at the beginning of August.

Earth, water and dense bodies cannot be heated at a glance.

They receive most heat in June, when the Sun is at its peak. They absorb and keep the heat which penetrated to the deep in relation to the density of the substance and the size of the body, wherefore the heat of June fuses with the heat of July and August.

The same applies to the cold in winter.

¹³ We can consider in the same way the second hour of the afternoon, which is warmer than the noon, in spite of the fact that the Sun is already setting.

In this case the air acts in the same way as the Earth in case above mentioned. As far as the Earth is considered, the changes are not so sudden. Also the influence of the body of the Earth joins in, or at least of its surface.

¹⁴ Regarding those facts, we can predict that September and October will be warmer than February and March, although in both cases the days will be of the same lenghth.