The earth’s magnetic field

Hold a soft iron bar pointing to the north and sloping downwards, and hammer it several times. It will become slightly magnetic.

The earth is surrounded by magnetic field lines, which meet the earth in Great Britain and North America at an angle between 60 and 80-degrees. When the iron is hammered, its magnet particles are affected by the earth’s magnetic field lines and point to the north. In a similar way, tools sometimes become magnetic for no apparent reason. If you hold a magnetized bar in an east-west direction and hammer it, it loses its magnetism.

Magnetism Field Lines

Lay a sheet of drawing paper over a magnet - of course you already know how to make a magnet - and scatter iron filings on it. Tap the paper lightly, and a pattern forms.

The filings form into curved lines and show the direction of the magnetic force. You can make the pattern permanent. Dip the paper into melted candle wax and let it cool. Scatter the iron filings on it. If you hold a hot iron
over the paper after the formation of the magnetic lines, the field lines, the pattern will be fixed.

Electric light

In many homes there is a voltage tester, generally in the form of a screwdriver. In its handle there is, amongst other things, a small neon tube, which you can easily remove. Hold one metal end firmly and rub the other on a piece of hard foam plastic which may be used for insulation. The lamp begins to glow as it is rubbed to and fro, and you can see this particularly clearly in the dark.

Since the plastic is soft, its layers are rubbed against one another by the movement of the lamp and become strongly charged with electricity. The electrons collect on the surface, flow through the core of the tiny lamp, and into the body which begins to glow .

The ancient Greeks had already discovered that amber attracted other substances when it was rubbed. They called the petrified resin ‘electron’. The power, which has caused such fundamental changes in the world since then therefore, gets its name - electricity.

Flash of lightning

Place a metal slice on dry glass, and on it a piece of hard foam plastic which you have rubbed well on your pullover. If you hold your finger near the handle of the slice, a spark jumps across.

When the negatively charged plastic is placed on the slice, the negative electric particles in the metal are repelled to the end of the handle, and the voltage between it and the finger becomes equalized. Plastic materials can become strongly charged. In warehouses, for example, metal stands for rolls of plastic are earthed, by the personnel because otherwise they often spark.

High Voltage

Place a flat baking tray on a dry glass, rub a blown-up balloon vigorously on a woolen pullover and place it on the tray. If you put your finger near the edge of the tray, a spark jumps across.

A voltage equalization occurs between the metal and the finger. Although the spark is discharged with several thousand volts, it is just as harmless as the sparks produced when you comb your hair. An American scientist discovered that a cat’s fur must be stroked 9,200.000.000 times to produce a current sufficient to light a 75-watt bulb for a minute.

Puppet dance

Lay a pane of glass across two books, with a metal plate underneath. Cut out dolls an inch or so high from tissue paper. If you rub the glass with a woollen cloth, the dolls underneath begin a lively dance. They stand up, turn round in a circle, fall, and spring up again.

The glass becomes electrically charged when it is rubbed with the wool, attracts the dolls, and also charges them. Since the two like charges repel each other, the dolls fall back on the plate, give up their charge to the metal and are again attracted to the glass.

Electric fleas

Rub a long-playing record with a woolen cloth and place it on a glass. If you toss some small silver-paper balls on to the record, they will jump away from one another in a zigzag motion.

If you then move the balls together with your fingers, they will hop fiercely away again.

The electricity produced on the record by rubbing is distributed in irregular fields. The balls take up the charge and are repelled, but are again attracted to fields with the opposite charge. They will also be repelled when they meet balls with the same charge.

Electrical ball game

Fix a piece of silver paper cut into the shape of a footballer on to the edge of a phonograph record, rub the record vigorously with a woolen cloth and place it on a dry glass. Put a tin can about two inches in front of the figure. If you hold a small silver-paper ball on a thread between them, it swings repeatedly from the figure to the can and back.

The electric charge on the record flows into the silver-paper figure and attracts the ball, it becomes charged, but is immediately repelled because the charges become equal, and goes to the can, where it loses its electricity. This process is repeated for a time.

Simple Electroscope

Bore a hole through the lid of a jam jar and push a piece of copper wire bent into a hook through it. Hang a folded strip of silver paper, from which you have removed the paper, over the back. If you hold a fountain pen, comb, or similar object, which has been electrically charged by rubbing on the top of the wire, the ends of the strip spring apart.

On contact with a charged object, electrical charges flow through the wire to the ends of the strip. Both now have the same charge and repel one another according to the strength of the charge.

Shooting puffed rice

Charge a plastic spoon with a woolen cloth and hold it over a dish containing puffed rice. The grains jump up and remain hanging on the spoon until suddenly they shoot wildly in all directions.

The puffed rice grains are attracted to the electrically charged spoon and cling to it for a time. Some of the electrons pass from the spoon into the puffed rice, until the grains and the spoon have the same charge. Since, however, like charges repel one another, we have this unusual drama.

Hostile balloons

Blow two balloons right up and join them with string. Rub both on a woolen pullover and let them hang downwards from the string. They are not attracted, as you might expect, but float away from each other.

Both balloons have become negatively charged on rubbing because they have taken electrons from the pullover, which has now gained a positive charge. Negative and positive charges attract each other, so the balloons will stick to the pullover. Similar charges, however, repel one another, so the balloons try hard to get away from each other.

Water bow

Once more rub a plastic spoon with a woollen cloth. Turn the water tap on gently and hold the spoon near the fine jet. At this point, the jet will be pulled towards the spoon in a bow.

The electric charge attracts the uncharged water particles. However, if the water touches the spoon, the spell is broken. Water conducts electricity and draws the charge from the spoon. Tiny water particles suspended in the air also take up electricity.

Therefore experiments with static electricity always work best on clear days and in centrally heated rooms.

Coiled Adder

Cut a spiral-shaped coil from a piece of tissue paper about 4 inches square, lay it on a tin lid and bend its head up. Rub a fountain pen vigorously with a woolen cloth and hold it over the coil. It rises like a living snake and reaches upwards.

In this case the fountain pen has taken electrons from the woolen cloth and attracts the uncharged paper. On contact, the paper takes part of the electricity, but gives it up immediately to the lid, which is a good conductor. Since the paper is now uncharged again, it is again attracted, until the fountain pen has lost its charge.

Pepper and salt

Scatter some coarse salt onto the table and mix it with some ground pepper. How are you going to separate them again?
Rub a plastic spoon with a woollen cloth and hold it over the mixture. The pepper jumps up to the spoon and remains sticking to it. The plastic spoon becomes electrically charged when it is rubbed and attracts the mixture. if you do not hold the spoon too low, the pepper rises first because it is lighter than the salt. To catch the salt grains, you must hold the spoon lower.

Clinging balloons

Blow up some balloons, tie them up and rub them for a short time on a woollen pullover. If you put them on the ceiling, they will remain there for hours.

The balloons become electrically charged when they are rubbed, that is, they remove minute, negatively charged particles, and called electrons, from the pullover. Because electrically charged bodies attract those, which are uncharged, the balloons cling to the ceiling until the charges gradually become equal. This generally takes hours in a dry atmosphere because the electrons only flow slowly into the ceiling, which is a poor conductor.

Light fan

Hold a light-coloured rod between your thumb and forefinger and move it quickly up and down in neon light. You do not see, as you might expect, a blurred, bright surface, but a fan with light and dark ribs.

Neon tubes contain a gas, which flashes on and off 50 times a second because of short breaks in alternating current. The moving rod is thrown alternatively into light and darkness in rapid sequence, so that it seems to move by jerks in a semicircle. Normally the eye is too slow to notice these breaks in illumination clearly. In an electric light bulb the metal filament goes on glowing during the short breaks in current.

Electro Buzzer

Nail board B and wooden blocks C and D onto board A (about 5 X 5 inches). Push an iron bolt F through a hole bored in B. Wind covered copper wire G 100 times round the bolt and connects the ends to a battery and to H respectively. Bore a hole through block C and wedge the fret saw blade H firmly into it so that its end is a short distance from bolt F. Hammer a long nail K through A and bend it so that its point rests in the middle of the saw blade. Oil the point of the nail. Use a piece of beading E as a key, with a rubber band P as spring and drawing pins M and N as contacts. Join all the parts with connecting wire (remove the insulation).

If you press the key down, you connect the electric circuit, bolt F becomes magnetic and attracts H. At this moment the circuit is broken at K and the bolt loses its magnetism. H jumps back and reconnects the current. This process is repeated so quickly that the saw blade vibrates and produces a loud buzz. If you wish to do Morse signaling with two pieces of apparatus, you must use three leads as in the lower circuit diagram.

Electro- magnet

Wind one to two yards of thin insulated wire on to an iron bolt and connect the bare ends of the wire to a battery. The bolt will attract all sorts of metal objects.

The current produces a field of force in the coil. The tiny magnet particles in the iron become arranged in an orderly manner, so that the iron has a magnetic north and South Pole. If the bolt is made of soft iron, it loses its magnetism when the current is switched off, but if it is made of steel it retains it.

Mysterious Circles

Push a length of copper wire through a piece of cardboard laid horizontally and connect the ends of the wire to a battery. Scatter iron filings on to the cardboard and tap it lightly with your finger. The iron filings form circles round the wire. If a direct current is passed through a wire or another conductor, a magnetic field is produced round it. The experiment would not work with an alternating current, in which the direction of the current changes in rapid sequence, because the magnetic field would also be changing continuously.

Mini-microphone

Push two pencil leads through the short sides of a matchbox, just above the base. Scrape off some of the surface, and do the same with a shorter lead, which you lay across the top. Connect the microphone with a battery and earphone in the next room. (You can take the earphone from a transistor radio.) Hold the box horizontal and speak into it. Your words can be heard clearly in the earphone.

The current flows through the graphite

Graphite Conductor

Connect a torch bulb with a battery by means of a pair of scissors and a pencil. The bulb lights up. From the long tongue of the battery, the negative pole, the current flows through the metal of the scissors to the
lamp. It makes it glow, and flows through the graphite shaft to the positive pole of the battery. Therefore graphite is a good conductor: so much electricity flows even through a pencil “lead” on paper, that you can hear crackling in earphones.

Coin current

Place several copper coins and pieces of sheet zinc of the same size alternately above one another, and between each metal pair insert a piece of blotting paper soaked in salt water. Electrical energy, which you can detect, is set free. Wind thin, covered copper wire about 50 times round a compass, and holds one of the bare ends on the last coin and one on the last zinc disk. The current causes a deflection of the compass needle.

In a similar experiment the Italian physicist Volta obtained a current. The salt solution acts on the metal like the sap in the potato in the previous experiment.

Electricity Potato battery

Stick finger-length pieces of copper and zinc wire one at a time into a raw potato. If you hold an earphone on the wires, you will hear distinct crackling.

An electric current causes the noise. The potato and wires produce an electric current in the same way as a torch battery, but only a very weak one. The sap of the potato reacts with the metals in a chemical process and also produces electrical energy. We speak of a galvanic cell because the Italian doctor Galvani first observed this process in a similar experiment in 1789.

Destroyed metal

Put a piece of aluminum foil with a copper coin on it into a glass of water, and let it stand for a day. After this the water looks cloudy and at the place where the coin was lying the aluminum foil is perforated.

This process of decomposition is known as corrosion. It often occurs at the point where two different metals are directly joined together. With metal mixtures (alloys) it is particularly common if the metals are not evenly distributed. In our experiment the water becomes cloudy due to
dissolved aluminum. A fairly small electric current is also produced in this process.

Burning iron

Would you have thought that even iron could be made to burn with a flame!

Twist some fine steel wool round a small piece of wood and hold it in a candle flame. The metal begins to blaze and scatter sparks like a sparkler.

The oxidation, which was slow in the previous experiment, is rapid in this case. The iron combines with the oxygen in the air to form iron oxide. The temperature thus produced is higher than the melting point of iron. Because of the falling red-hot particles of iron it is advisable to carry out the experiment in a basin.

Burning without a flame

Press a handful of steel wool firmly into a glass tumbler and moisten it. Invert the tumbler over a dish containing water. At first the air in the tumbler prevents the water entering, but soon the level of water in the dish becomes lower while that in the glass rises.

After the steel wool is moistened, it begins to rust. The iron combines with the oxygen in the air, and we call this process combustion or oxidation. Since the air consists of about one-fifth oxygen, the water rises in the tumbler until after some hours it fills one-fifth of the space.

However, an imperceptible amount of heat is set free in the process.

Fire extinguisher

Light a candle stump in an empty glass, and mix in another glass - as in the previous experiment - a teaspoonful of bicarbonate of soda with some vinegar and let it froth. If you tilt the glass over the candle, the flame goes out.

The carbon dioxide formed in the chemical reaction in the top glass displaces the air needed for the flame, because it is heavier, and because it is non-combustible the flame is smothered. Many fire extinguishers work in the same way: the sprayed foam consists of bubbles filled with carbon dioxide. It surrounds the flame and blocks the supply of oxygen.

Gas balance

Fix two plastic bags to the ends of a piece of wooden beading about 18 inches long and let it swing like a balance on a drawing pin. Pour some bicarbonate of soda and some vinegar into a glass. It begins to froth, because a gas is escaping. If you tilt the glass over one of the bags, the
balance falls.

The gas, which is given off during the chemical reaction, is carbon dioxide. It is heavier than air, so it can be poured into the bag and weighed. If you were to fill a balloon with the gas it would never rise, and for this purpose other gases are used, which are lighter than air.

Gas pipe

Roll a thin piece of tin foil round a pencil to make a tube about four inches long, and hold it with one end in the middle of a candle flame. If you hold a burning match at the other end of the tube, a second flame will be lit there.

Like all solid and liquid fuels, searing produces combustible gases when heated, and these accumulate inside a flame. They burn, with the oxygen of the air, in the outer layer and tip of the flame. The unburnt searing vapor in the middle can be drawn off, like town gas from the gas works.

Jet of flame

Light a candle, let it burn for a while, and blow it out again. White smoke rises from the wick. If you hold a burning match in the smoke, a jet of flame shoots down to the wick, and it re-lights.

After the flame is blown out the steam is still so hot that it continues to evaporate and produce a vapor. But as this is combustible, it can be re-lighted at once by a naked flame. The experiment shows that solid substances first become gaseous at the surface before they will burn in a supply of oxygen.

Sugar fire

Place a piece of cube sugar on a tin lid and try to set it alight.

You will not succeed. However, if you dab a corner of the cube with a trace of cigarette ash and hold a burning match there, the sugar begins to burn with a blue flame until it is completely gone.

Cigarette ash and sugar cannot be separately ignited, but the ash initiates the combustion of the sugar. We call a substance, which brings about a chemical reaction, without itself being changed a catalyst.

Transfer pictures

Photos and drawings from newspapers can be copied easily. Mix two spoonfuls of water one spoonful of turpentine and one spoonful of liquid detergent and dab this liquid with a sponge on the newspaper page.

Lay a piece of writing paper on top, and after vigorous rubbing with a spoon the picture is clearly transferred to the paper.

Turpentine and liquid detergent when mixed form an emulsion, which penetrates between the dye and oil particles of the dry printing ink and make it liquid again. Only newspaper printing ink can be dissolved, though.

Bleached rose

A piece of sulfur is ignited in a jam jar. Since a pungent vapor is produced, you should do the experiment out-of-doors. Hold a red rose in the jar. The color of the flower becomes visibly paler until it is white.

When sulfur is burned, sulfur dioxide is formed. As well as its germicidal action in sterilization, the gas has a bleaching effect, and the dye of the flower is destroyed by it. Sulfur dioxide also destroys the chlorophyll of plants, which explains their poor growth in industrial areas, where the gas
pollutes the air.

Invisible ink

If you ever want to write a secret message on paper, simply use vinegar, lemon, or onion juice, as the invisible ink. Write with it as usual on white writing paper. After it dries the writing is invisible. The person who receives the letter must know that the paper has to be held over a candle flame: the writing turns brown and is clearly visible.

Vinegar, and lemon or onion juice, cause a chemical change in the paper to a sub- stance’ similar to cellophane. Because its ignition temperature is lower than that of the paper, the parts written on singe.

Violet becomes red

If you ever come across an anthill in the woods, you can there and then do a small chemical experiment. Hold a violet flower, e.g. a bluebell, firmly over the ants. The insects feel threatened and spray a sharp smelling liquid over the flower.

The places hit turn red. The ants make a corrosive protective liquid in their hindquarters. You notice it if an ant nips you, though it is generally quite harmless. Since the flower turns red where the drops fall, you know
that they are acid. The acid is called formic acid.

Colour Magic

Cut a red cabbage leaf into small pieces and soak in a cup of boiling water. After half an hour pour the violet-coloured cabbage water into a glass. You can now use it for crazy colour magic. Place three glasses on the table, all apparently containing pure water. In fact only the first glass contains water, in the second is white vinegar and in the third water mixed with bicarbonate of soda. When you pour a little cabbage water into each glass, the first liquid remains violet, the second turns red
and the third green. The violet cabbage dye has the property of turning red in acid liquids and green in alkaline. In neutral water it does not change colour. In chemistry one can find out whether a liquid is acid or alkaline by using similar detecting liquids (indicators).

Two Coloured Flower

Dilute red and green fountain pen inks with water and fill two glass tubes each with one colour. Split the stem of a flower with white petals, e.g. a dahlia, rose or carnation, and place one end in each tube. The fine veins of the plant soon become coloured, and after several hours the flower is half-red and half blue.

The coloured liquid rises through the hair-fine channels by which, the water and food are transported. The dye is stored in the petals while most of the water is again given off.

Leaf skeleton

Place a leaf on blotting paper and tap it carefully with a clothes brush, without pressing too hard or moving sideways. The leaf is perforated until only the skeleton remains, and you can see the fine network of ribs and
veins.

The juicy cell tissue is driven out by the bristles and sucked up by the blotting paper. The ribs and veins consist of the firmer and slightly lignified ( Cell walls strengthened and thickened ) framework and resist the brush.

Zig-zag growth

Lay pre-germinated seeds on a sheet of blotting paper between two panes of glass, pull rubber bands around the panes and place in a water container in a window. Turn the glass panes with the shoots onto a different edge every two days. The roots always grow downwards and the stem grows upwards.

Plants have characteristic tendencies. Their roots strive towards the middle of the earth and the shoots go in the opposite direction. On slopes the roots of trees do not grow at right angles to the surface into the ground, but in the direction of the middle of the earth.

Rain in a jar

Place a green twig in a glass of water in sunlight. Pour a layer of oil on to the surface of the water and invert a large jar over the lot. After a short time, drops of water collect on the walls of the jar. Since the oil is impermeable, the water must come from the leaves. In fact the water which the plant absorbs is given off into the air through tiny pores in the epidermis of the leaf. Air saturated with moisture and warmed by the sun
deposits drops like fine rain on the cool glass.

Ghostly noise

Fill a wineglass to overflowing with dried peas, pour in water up to the brim, and place the glass on a metal lid. The pea heap becomes slowly higher and then a clatter of falling peas begins, which goes on for hours.

This is again an osmotic process. Water penetrates into the pea cells through the skin and dissolves the nutrients in them. The pressure thus formed makes the peas swell. In the same way the water necessary for life penetrates the walls of all plant cells, stretching them. If the plant obtains no more water, its cells become flabby and it wilts.

Rising Sap

Make a deep hole in a carrot and fill it with water in which you have dissolved plenty of sugar. Close the opening firmly with a bored cork, and push a plastic straw through the hole. Mop up any overflowing sugar solution, and seal the joints with melted candle wax. Put the carrot into water and watch: after some time the sugar solution rises into the straw.
The water particles can enter the carrot through the cell walls, but the larger sugar particles cannot come out. The sugar solution becomes diluted and rises up the tube. This experiment on osmosis illustrates how plants absorb water from the soil and carry it upwards.

Secret path

Dissolve a teaspoonful of salt in a glass of water and cover it tightly with parchment paper. Place the glass upside down in a dish containing water strongly coloured with vegetable dye. Although the parchment paper has no visible holes; the water in the glass is soon evenly coloured. The tiny particles of water and dye pass through the invisible pores in the parchment paper. We call such an exchange of liquids through a permeable membrane, osmosis.


All living cells are surrounded by such a membrane, and absorb water and dissolved substances in this way.

Automatic watering

Fill a bottle with water and place it upside down and half-buried in soil in a flower box. An air bubble rises up in the bottle from time to time, showing that the plants are using the water. The water reservoir is enough for several days, depending on the number of plants and the weather. Water only flows from the bottle until the soil round it is soaked. It starts to flow again only when the plants have drawn so much water from the soil that it becomes dry, and air can enter the bottle. One notices that plants can take water more easily from loose soil than from hard.

The sun brings life

Fill a large glass jar with fresh water and place in it several shoots of water weed.

Place the jar in sunlight, and at once small gas bubbles will rise in the water. Invert a funnel over the plants and over it a water-filled glass tube. The gas, which is given off by the plants slowly, fills the tube.

Plants use sunlight. With its help, in the presence of chlorophyll, they make their building material, starch, from water and carbon dioxide, and give off oxygen. Oxygen has actually collected in the glass tube. If you remove the tube and hold a glowing splint in it, the splint will burn brightly.

Maze

Plant a sprouting potato in moist soil in a pot. Place it in the corner of a shoe box and cut a hole in the opposite side. Inside stick two partitions, so that a small gap is left. Close the box and place it in a window. After a couple of days the shoot has found its way through the dark maze to the light.

Plants have light-sensitive cells, which guide the direction of growth. Even the minimum amount of light entering the box causes the shoot to bend. It looks quite white, because the important green colouring material, chlorophyll, necessary for healthy growth, cannot be formed in the dark.

World time clock

The earth rotates in 24 hours from west to east once on its axis. In this time the sun shines on all regions of the globe one after the other and determines their time of day. To enable a practical calculation of the time, the earth is divided into 24 time zones, which are very simply shown on the map below.
Since in a few areas, which belong together, a uniform time has been
introduced, the boundaries of the time zones sometimes run along state boundaries. For example, Mexico has Central time. The West European countries including Great Britain has together with the Middle European countries, Middle-European time.

According to the map, when it is 13.00 hours there it is only 7 o’clock in the morning on the East Coast of the U.S.A. in Japan it is already 21 .00 hours and on the right edge (dateline) a new day is beginning.

The time zones are shown on the world time disk pictured below.

Copy or stick this onto a piece of cardboard and cut it out. Color the panel corresponding to time zone were you live red. Remove the casing and glass from an alarm clock, push the minute hand through the hole in the paper disk and fix it firmly to the hour hand. Make sure that the red-colored panel is exactly over the hour hand. If you rotate the disk with this, it should not stick. The clock will tell you all time of the day on the earth. Read off first on the red panel the time of the place where you live.

If you rotate the disk to the left, you will find the time zones of places west of you. In each panel, the time is an hour earlier. If you rotate to the right, you will find the places east of you. In each panel the time is an hour later. The outer circle continues into the inner circle at the crossed arrows and vice-versa. For example: in New York it is 6.15 in the morning. Then it is already 20.15 in Tokyo and in New Zealand a new day will begin in 45 minutes. Or in London it is 20.03. What time is it in
San Francisco? Look at the world map: San Francisco lies in the time zone of Los Angeles. On the rotating disk go to the left to the Los Angeles panel. The time is: 11.03.

Watch as a compass

Hold a watch horizontally, with the hour hand pointing directly to the sun. If you halve the distance between the hour hand and the 12 with a match, the end of the match points directly to the south.

In 24 hours the sun ‘moves’, because of the earth’s rotation, once around the earth. But the hour hand of the watch goes twice round the dial. Therefore before midday we halve the distance from the hour hand to the 12, and after midday from the 12 to the hour hand. The match always points to the south. At midday, at 12 o’clock, the hour hand and the 12 both point to the sun standing in the south.

Sun clock

Place a flowerpot with a long stick fixed into the hole at the bottom in a spot, which is sunny, all day. The stick’s shadow moves along the rim of the pot as the sun moves. Each hour by the clock mark the position of the shadow on the pot. If the sun is shining, you can read off the time. Because of the rotation of the earth the sun apparently passes over us in a semi-circle. In the morning and evening its shadow strikes the pot superficially, while; it midday, around 12 o’clock, the light incidence is greatest. The shadow can be seen particularly clearly on the sloping wall of the pot.

Image of the Sun

Place a pair of binoculars in an open window in the direct path of the suns rays.
Stand a mirror in front of one eyepiece so that it throws an image of the sun on to the
opposite wall of the room. Adjust the mirror until the image is sharp, and darken the
room.

You would risk damaging your eyes if you looked directly at the sun through
binoculars, but you can view the bright disc on the wall as large and clear as in the
movies. Clouds and birds passing over can also be distinguished and. if the binoculars
are good even sunspots. These are a few hot areas on the glowing sphere, some so big
that many terrestrial globes could fit into them. Because of the earth’s rotation, the
sun’s image moves quite quickly across the wall. Do not forget to re-align the
binoculars from time to time onto the sun. The moon and stars cannot be observed in
this way because the light coming from them is too weak.