My Science School

•  Fix scratched surfaces

If your acrylic bath is scratched, you can fix it with metal polish. Apply the polish with a soft cloth using a circular motion. The light abrasive in the polish lifts out most fine scratches. To smooth out deeper nicks and scrapes, dampen them with a bit of water and then gently rub with a piece of very fine wet-and-dry abrasive paper before polishing.

Scratches on enamel baths and surfaces can be covered with a few thin coats of enamel touch-up paint (available from most hardware shops) or white correction fluid. Clean the damaged area with some methylated spirits on a cotton wool ball and then sand lightly with wet-and-dry abrasive paper. Let the methylated spirits fully evaporate before applying the paint.

•  Fill tubs before sealing

Before you seal around a bath, fill the bath with water. The extra weight will widen the gap in the joint between the bath and the wall, which makes for a thicker seal that's less likely to crack or tear later on.

•  A smarter, simpler way to save water

Some people put bricks inside their toilet cisterns to reduce the amount of water per flush. It's a good way to conserve water, but it can be bad for the toilet because bricks submerged in water often break up and the bits can get into the flushing mechanism. A better option is to use old plastic bottles filled with sand or water. Remove any labels and check that the bottle is tightly sealed before placing it in the cistern.

•  No plunger, no problem

Use a hollow rubber ball or tennis ball instead. Secure the ball in a vice and cut it in half with a hacksaw or a utility knife. To clear a blocked waste pipe, fit the concave side over the waste outlet and press down with your palms or the base of your thumbs to create pressure.

•  Clamp down on loose plungers

A plunger with a loose handle makes every job more difficult and can even be dangerous if the handle slips out or breaks off. If your plunger handle is easily separated from the suction cup, tighten it by placing a hose clamp around the base of the cup so that it is firmly clamped to the handle.

•  Saucer as sink shield

Before taking apart a tap in a sink without a plug, take a small plate or saucer and simply place it upside down over the drain to prevent any small pieces from getting lost.

•  Loosen a stuck tap

If you've tried everything, but a tap handle won't budge, try pouring fizzy drink such as cola or lemonade over the tap. Give the carbonation 5-10 minutes to loosen any rust or corrosion around the tap — followed by a few gentle strikes with a rubber mallet, and it'll loosen with ease.

•  Stop a sink or tub

If your drain plug has disappeared, but you need to stop the water in the sink or bathtub, here's a stopgap solution. Place a plastic lid over the drain. The vacuum created keeps the water from slip-sliding away.

•  Easy turn-off

It is frustrating when you want to turn the water off at the mains, only to find that the stop tap is jammed tight. It can usually be loosened by the judicious application of WD-40 and/or heat — but, to avoid it happening again, try to remember to operate it every month or so and always close it a quarter turn from fully open when you leave it. This way it will work freely when you need it.

•  Hose off pipe leaks

When you need a quick patch for a leaking water pipe, cut off a section of old garden hose or rubber tubing that's longer than the affected area of pipe. Slice it lengthways, and then fit the hose over the leak. Wrap it well with waterproof tape and secure it with three hose clamps: one on each end and one in the middle.

•  Blow-dry a frozen pipe

If a water pipe freezes during winter, close the main valve on the water meter and open the nearest tap. Then, starting at the tap, use a hair dryer on a medium setting to thaw out the pipe. Be sure to keep the drier moving all the time so that the pipe doesn't get too hot in one spot; a sudden shift in temperature can cause pipes to crack. After it thaws, cover the pipe in thick foam insulating material to keep it from freezing in the future.

•  Rub out scorch marks

If you spot a scorch mark on a laminated benchtop, don't use abrasive powder; chances are you'll only remove the finish. If the burn isn't too deep, buff it out with car polish or a mixture of toothpaste and bicarbonate of soda.

•  A fast fix for dents

If the colour hasn't been altered, you can disguise dents and scratches on practically any kitchen surface — including wood, glass and even some kinds of tiles — with clear nail polish. Brush on the polish in thin coats, letting it dry between applications. When you're finished, smooth the polish with a piece of very fine grit sandpaper, then buff the area with a soft cloth.

•  Check the fridge door gasket

If your fridge or freezer is more than five years old, inspect its door gasket for leaks at least once a year. The easiest method is to place a piece of paper — or a bank note — halfway inside, shut the door, and then tug on the paper. Repeat the process in several spots around the seal. The paper should hold firmly; if it's easy to pull out, the gasket needs to be repaired or replaced.

•  Add ballast to your freezer

Freezers work at maximum efficiency only when they are at least two-thirds full. If you don't have enough food to freeze, add some bulk by filling a few plastic drinks bottles with water and placing them in the freezer. You can easily remove the ice ballast when there's food to replace it.

•  No-stick kitchen drawers

Most kitchen drawers work on a guide-and-track system. That is, rounded guides on the drawer keep it moving back and forth on tracks mounted inside the cabinet. Accumulations of dust and other impediments can slow down drawers or cause them to stick. Keep them moving freely by spraying the tracks and guides with a little WD-40 once or twice a year.

•  Stop cupboard doors from banging

If your wooden cupboard doors always close with a bit of a bang, soften the blow by sticking bumpers at each door's top and bottom corners. Inexpensive door bumper pads are one solution, but perhaps a little too obvious for the creative do-it-yourselfer. Instead, try pressing small circular padded adhesive dressings into service, testing to see if you need a double layer to silence the bang.

•  Repair instead of replacing

If you've ever bought a replacement part for a kitchen appliance, you are probably still in recovery from the shock of the high price. The truth is many non-moving parts can be easily repaired for very little cost. For instance, a broken handle on a microwave oven or a cracked dishwasher arm can often be easily reattached with some two-part epoxy adhesive. Likewise, a little silicone sealant can be used to patch a small crack in your refrigerator's door gasket, while a few strips of gaffer tape can usually mend broken parts on a fridge door shelf. Remember that you only need to replace parts that really can't be fixed.

•  Make customized wood filler

When working with specific types of wood, save some of the finest sawdust produced by your sanders. Mix a handful of the sawdust with ordinary woodworking adhesive until it becomes a thick paste, and then overfills the crack. Let it dry, then lightly sand. Note: cracks filled with adhesive-based filler will not accept stain in the same way that solid wood does.

•  Instant wood filler

If you need some wood filler in a hurry for an emergency repair on an inexpensive piece of furniture, mix a couple of tablespoons of ready-mixed all-purpose filler with instant coffee until you achieve the desired shade of brown. Fill in the crack and smooth with a damp rag.

•  Pluck some filler

An old guitar plectrum makes a great tool for applying small amounts of filler to fill nail holes and small cracks in wood. An easy solution with no strings attached!

•  Soften wood filler

Acetone-based cellulose wood fillers are designed to dry quickly. If you notice that your acetone filler has started to solidify in the can, you can soften it by adding a little acetone nail polish remover. Stir in just enough to bring the filler to the right consistency or it will become too runny to use. Note: it is not possible to save filler that has already hardened.

•  Get rid of glue with vinegar

Don’t despair when you get a hardened glob of adhesive on your woodwork. Cover it with a rag soaked in warm white vinegar then leave it overnight. The adhesive will slide off with ease in the morning. Vinegar will also soften old glued joints — and even that last bit of wood-working adhesive that's hardening in the bottom of the bottle. Just add a few drops of vinegar to the bottle and let it sit for an hour or two. Shake well, drain the vinegar and repeat the process as necessary.

•  The last straw for glue spills

Keep some plastic drinking straws nearby when working with wood; they come in handy when working with adhesives and lubricants. If you use too much wood adhesive along a seam, for instance, simply fold a straw in half and use the folded edge to scoop up the excess.

•  Flip a stripped finish

Stop off in the kitchen before stripping a piece of furniture. The flat, flexible blade on an old plastic spatula is exactly what you need to scrape off used stripper. Hold the spatula by the blade in a reverse position and push it in a straight, steady motion to remove the old finish.

•  Better ways to stain

Put old pairs of pantihose to work when staining furniture. Rolled-up pantihose or stockings make a great alternative to a cotton cloth or a rag. Not only do they drip less, but they also won't leave any lint behind.

A spare paint roller also makes a terrific stain applicator. Cut a 22-cm roller into three equal pieces. Whether fixed to an applicator or held in your hand, a roller holds more stain than a brush and applies it more evenly than a rag.

•  Stop stripper drips

The next time you need to strip a table or a chair, place the legs inside cleaned, empty soup or baked bean cans. The cans will catch the drips, which, besides keeping your work space cleaner, will allow you to re-use the stripper for a second coat.

•  Baby oil the end grain

If you'd like to save a couple of dollars, don't spend them on a proprietary sealer when finishing your next woodworking project.

Instead, seal the end grain with unscented baby oil. It will work just as well as the stuff that you can buy from a hardware shop. It keeps the colour uniform by preventing the end from soaking up too much stain.

•  The easy way to sand around curves

Wrap a tennis ball in sandpaper and use it to sand curves when refinishing furniture. A tennis ball is just the right shape and size to fit comfortably in your hand.

•  Instant fix for scratched woodwork

If you notice several fresh, light scratches on a dark-wood wall unit and need to find a quick fix, just go to the kitchen, get a small cup or container and mix 1 teaspoon instant coffee in 1 tablespoon vegetable oil or water. Apply the mixture with a cotton wool ball. (Don't use this on valuable antiques or shellac finishes.)

•  Cover scratches in leather

You can camouflage unsightly scratches in leather furniture using a permanent marker in a similar shade. Before you start, test the marker on an inconspicuous part of the chair or sofa to make sure that it's a good match. Work slowly and carefully when tracing over the scratch. Medium or fine-point markers work best overall; extra-fine tips may deepen a scratch while thick markers often have a visible ‘edging’ around repairs.’

•  Check out the market

These days — especially with the advent of the Internet — you can get a whole range of wood-care products, previously available only to professionals. And they're all available in a range of wood shades. For repairing scratches (and filling small cracks and holes), try these:

1.  Burnishing cream (superficial scratches)


2.  Wax filler sticks (and shellac filler sticks)


3.  Retouch crayons


4.  Touch-up pens

•  Homeopathic scratch care

Many light scratches on wood can be repaired without an expensive trip to a hardware shop. That's because masking a scratch is simply a matter of covering it up or adequately lubricating the exposed wood fibres. What's amazing is the number of items that you probably already have around your home that can get the job done. Regardless of which method you use, wax the surface when done.

1.  Conceal scratches with closely matched shoe polish, a melted crayon or a permanent marker.


2.  Use the meat of a Brazil nut, walnut or pecan. Rub the nut over the scratch several times, and then vigorously massage the oil into the scrape with your thumb.


3.  Can't find the nutcracker? Rub in a little peanut butter or mayonnaise instead. Wipe it off with a damp rag after 30 minutes or so.


4.  If that's too messy, try a little baby oil or mix 1 tablespoon olive oil or vegetable oil with 1 tablespoon lemon juice. Apply it with a soft cloth, and then buff it off after 30-45 minutes.


5.  Cover scratches with a generous amount of petroleum jelly. Let it soak in for 24 hours, then remove the excess with a soft cloth.

•  Wax away hairline scratches

High-gloss lacquer finishes are prone to developing hairline scratches when dishes or other items are slid across their surface. You can often get rid of these light scratches with car wax, which contains a light abrasive. Test the wax first on a bottom edge or some other inconspicuous area first, to make sure the wax doesn't discolour or damage the finish. Once you're ready, apply the wax to a soft cloth and polish using a steady circular motion.

•  Solution for sunlight damage

Sunlight can wreak havoc on your furniture, but you can restore it to its former lustre with plain old petroleum jelly. Use a soft cloth to rub a good amount into the wood until the finish perks up. Remove any excess with a clean cloth, and then polish the wood to renew its shine.

•  Tea time for grime

To remove accumulated grime on wooden furniture, put two tea bags in a litre of boiling water and allow to cool. Dip a soft cloth into the solution, wring it out and then test it in an inconspicuous area on the table. If you're pleased with the results, wipe down one section of the piece at a time. Continue dipping, wringing and wiping until all the old polish has been removed. Let it dry, buff with a soft dry cloth, then stand back and watch it glow.

•  Steam out a dent

You can sometimes repair a small, shallow dent in wooden furniture with a warm, damp cloth and a steam iron. Fold the cloth and place it over the dent, then press down with the tip of a warm iron for several seconds. If the dent doesn't swell, repeat, but don't overdo it. You need to provide just enough moisture to swell the wood back to its original size. (Don't do this on shellacked or painted finishes.)

•  Repair veneer edging with an iron

If veneer stripping or edging is bulging or popping up from the surface of a piece of furniture, lay a warm, damp cloth over it and press down with the tip of a warm iron for several seconds. Once it's flattened, roll the edging with a rolling pin.

•  Unstick a drawer

Wooden drawers can become stuck for all sorts of reasons, but the most common cause is excessive humidity. Although you can't see it, the wood fibres actually swell from the extra moisture in the air. To shrink them back to their original size, use a hair dryer on a warm setting, directing it to the drawer slides and the drawer itself — which should open with ease after a few minutes. For stuck drawers that are more stubborn, try rubbing the sides, bottom edges and slides with lip balm, a bar of soap or paraffin wax or beeswax.

•  Lubricate metal drawer runners

Rust and other deposits can cause metal drawer runners to seize up or to move unevenly. Keep them running smoothly and free of rust by lubricating them occasionally with a smear of petroleum jelly or a squirt of WD-40.

•  Hassle-free hardware

If you want to keep the shine in decorative brass handles and knobs, give them a coat of clear nail varnish or clear lacquer. This simple task will provide years of protection against the damage wrought by skin oils and tarnishing.

•  Revive sagging cane seats

The more use it gets, the more a cane seat is likely to sag. To tighten a baggy seat, first soak two or three tea towels in hot water and wring them out lightly. Then turn the chair over and lay the hot towels on the bottom of the seat for about 30 minutes. Remove the towels and let the seat air-dry and then give the cane at least 12 hours to shrink back into place. The revived seat will be tighter and firmer to sit on.

•  Tighten loose joints

A bit of woodworking adhesive is usually all that you need to secure a wobbly chair leg or rail. But if the joint is very loose, adhesive alone may not do the job. An easy way to solve the problem is to increase the width of the tenon (the contoured end of the loose piece) by coating it with wood adhesive and wrapping it with cotton thread or by adding a wood shaving. (If you decide on the latter, choose a shaving that's uniformly thick for a consistent fit.) Let the adhesive dry, and then glue the tenon back into the mortise.

• Reglue it right

Most wobbly furniture can be fixed by simply regluing the parts back together — but since new glue won't stick to old dried glue, the key is to get rid of the old stuff. One of the best tools for getting rid of dried glue is the small wire-bristle brush you can get for cleaning car battery terminals. The external brush (shaped like a tiny fir tree) is ideal for removing glue from mortises and holes, while the internal brush is perfect for scraping dried glue from small tenons and dowel ends.

•  Paste over a minor burn

Although fewer people smoke in their homes these days, burn marks on wooden furniture are a more common problem than you might think. If the scorch doesn't go below the finish, you can usually rub it out with a paste made of fine ash (wood or cigarette ash) and lemon juice (2 parts ash to 1 part juice). Wipe the area clean, then polish and wax.

•  Use grandma's fragrant warming tip

Increase the warmth and moisture level inside your home on bitterly cold days by simply simmering a large pan of water on the stove. Don’t forget to periodically check the pan and refill the water as needed. Throw a few cloves, some orange peel and one or two cinnamon sticks into the pot and you'll have a delightful air freshener as well.

•  Get lit up about draughts

To pinpoint the often mysterious source of draughts — and where you’ll need to add or renew any draught-proofing — wait for a windy day, then light a candle. Start with the window or door nearest the draught. Hold the candle in a bottom corner of the frame and slowly raise it. The flame should travel up in a straight line; when it moves sharply in one direction or another, you've probably located a leak. Repeat this process for all the sealed openings around your house to pinpoint draughts.

•  Block door draughts

A draughty door will raise your fuel bill and make you feel uncomfortable. Until you can replace the draught-proofing, try blocking the draughts under doors with a homemade door ‘sausage’. Get an old long sock or cut a sleeve off an old shirt and fill it with sand, rice or foam padding weighed down with a few small stones. Sew the open ends shut and keep it against the crack at the bottom of the door. For safety's sake, prevent stumbles by spray-painting the draught-blocker a bright colour.

•  Cooling energy-savers

Buying a bigger air-conditioning unit for a room won't automatically keep you more comfortable during a long, hot summer. In fact, room air-conditioners that are too big for the room they are servicing will perform less efficiently and cost you a lot more to run. And don't forget that air-conditioning may not be the answer to everyone's cooling needs. Follow these easy tips for staying cool in summer:

1.  Use whole-house fans to pull cool air through the house and exhaust warm air through the roof space


2.  Don't set the thermostat at a colder setting than normal when you turn on an air-conditioner. It won't cool the house faster and may result in excessive cooling.


3.  Don't put lamps or TV sets near a thermostat as it will respond to the heat.

•  Hot water money-savers

If you insulate both the hot-water storage tank and the first metre or so of pipes running from the water tank, you can save some serious money on your heating bill. But remember not to cover the tank's top, bottom, thermostat or the pilot flame, and don't hesitate to get help from a professional. Storage tanks have relatively short lifespans, so when your tank is about seven years old, start looking around for energy-saving replacement options. Comparing prices will help ensure the best deal, and although the initial outlay may be more than conventional tanks, you'll save money in the long run by saving energy.

•  Degrease a dirty fan

Even occasional use can cause an extractor fan to collect dust and grime on its blades and grilles. The build-up of dirt will reduce the fan's air output and, worse, place unwanted stress on the machine’s motor.

To clean a dirty fan (which you should do at least once a year), unplug at the socket or turn off at the wall switch, and remove the housing. Vacuum off any loose dust using a soft brush attachment, then wipe down the blade and grilles with a rag or sponge dipped in a solution of ¼ cup (60ml) ammonia and ¼ teaspoon washing-up liquid in 5 litres warm water. Make sure that all the parts are dry before you reassemble them.

Credit: Reader's Digest

          Radar works in the same way as an echo. When you shout loudly at a distant wall, you will hear the echo of your voice a few seconds later. This is because the sound waves hit the solid wall and bounce back towards you. Radar uses high-frequency waves that travel much faster and much further. The radar sends out a short burst of radio waves and then listens for an echo, which tells it how far away the target is, and what it is made of.

          Airplane pilots get around this difficulty using radar, a way of "seeing" that uses high-frequency radio waves. Radar was originally developed to detect enemy aircraft during World War II, but it is now widely used in everything from police speed-detector guns to weather forecasting. Let's take a closer look at how it works!

          We can see objects in the world around us because light (usually from the Sun) reflects off them into our eyes. If you want to walk at night, you can shine a torch in front to see where you're going. The light beam travels out from the torch, reflects off objects in front of you, and bounces back into your eyes. Your brain instantly computes what this means: it tells you how far away objects are and makes your body move so you don't trip over things.

          Radar works in much the same way. The word "radar" stands for radio detection and ranging—and that gives a pretty big clue as to what it does and how it works. Imagine an airplane flying at night through thick fog. The pilots can't see where they're going, so they use the radar to help them.

          An airplane's radar is a bit like a torch that uses radio waves instead of light. The plane transmits an intermittent radar beam (so it sends a signal only part of the time) and, for the rest of the time, "listens" out for any reflections of that beam from nearby objects. If reflections are detected, the plane knows something is nearby—and it can use the time taken for the reflections to arrive to figure out how far away it is. In other words, radar is a bit like the echolocation system that "blind" bats use to see and fly in the dark.

          The most detailed information about Venus was acquired by a space probe called Magellan. Launched in 1989, Magellan travelled to Earth's neighbour and spent three years building a complete map of the planet. Flying as low as 294km (183 miles) above the surface, Magellan bounced radar pulses off the solid ground beneath and sent the data back to Earth to he analyzed. It measured strips of land 24km (14 miles) wide and 10,000km (6000 miles) long each time it circled the planet, while its altimeter measured its height above the surface.

          The Magellan spacecraft was the first planetary explorer to be launched by a space shuttle when it was carried aloft by the shuttle Atlantis from Kennedy Space Center in Florida on May 4, 1989. Atlantis took Magellan into low Earth orbit, where it was released from the shuttle's cargo bay and fired by a solid-fuel motor called the Inertial Upper Stage (IUS) on its way to Venus. Magellan looped around the Sun one-and-a-half times before arriving at Venus on August 10, 1990. A solid-fuel motor on the spacecraft then fired, placing Magellan into a near-polar elliptical orbit around Venus.

          Spacecraft carried a sophisticated imaging radar, which was used to make the most highly detailed map of Venus ever captured during its four years in orbit around Venus from 1990 to 1994. After concluding its radar mapping, Magellan also made global maps of Venus's gravity field. Flight controllers then tested a new maneuvering technique called aero braking, which uses a planet's atmosphere to slow or steer a spacecraft. The spacecraft made a dramatic plunge into the thick, hot Venusian atmosphere on October 12, 1994, and was crushed by the pressure of Venus's atmosphere. Magellan's signal was lost at 10:02 Universal Time (3:02 a.m. Pacific Daylight Time) that day.

          The Magellan mission was divided up into "cycles" with each cycle lasting 243 days (the time necessary for Venus to rotate once under the Magellan orbit). The mission proceeded as follows:

Magellan Assembly

          On May 4, 1989, the Magellan spacecraft was deployed from the shuttle. The spacecraft is topped by a 3.7-meter (12-foot) diameter dish-shaped antenna that was a spare part left over from the Voyager program. The long, white, horn-shaped antenna, attached just to the left of the dish antenna, is the altimeter antenna that gathers data concerning the surface height of features on Venus. Most of the spacecraft is wrapped in reflective white thermal blankets that protect its sensitive instruments from solar radiation. 

Deployment

          The Magellan spacecraft's deployment from the shuttle Atlantis' cargo bay was captured by an astronaut with a hand-held camera pointed through the shuttle's aft flight deck windows. Deployment occurred in the early evening of May 4, 1989, after Atlantis had carried Magellan and its Inertial Upper Stage (IUS) booster rocket, into low Earth orbit. Once the shuttle was safely away from the spacecraft, the IUS ignited and placed Magellan on course for its 15-month journey to Venus.

Magellan Orbiting Venus

          On August 10, 1990, Magellan entered into orbit about Venus, as depicted in this artist's view. During its 243-day primary mission, referred to as Cycle 1, the spacecraft mapped well over 80 percent of the planet with its high-resolution Synthetic Aperture Radar (SAR). The spacecraft returned more digital data in the first cycle than all previous U.S. planetary missions combined.

          Venus’ atmosphere is formed from clouds of carbon dioxide, nitrogen and sulphuric acid. This heavy layer of clouds is over 30km (18 miles) deep in some places, meaning that no part of the planet’s surface can be seen with the naked eye. Only since the 1970s have scientists been able to “look” past these clouds to see the solid ground beneath. This has mainly been done with equipment mounted on space probes. Radar technology allows probes to record the geography of the planet, and to produce a map of surface features.

          The clouds of Venus are its defining characteristic. We can see the surface of Mars and Mercury, but the surface of Venus is shrouded by thick clouds. For most of history, astronomers had no idea what was beneath those clouds, and they imagined a tropical world with overgrown vegetation and constant rainfall. They couldn’t have been more wrong.

          The climate of Venus isn’t tropical at all; it’s hellish. Temperatures on the surface of Venus approach 475°C and the atmospheric pressure is 93 times what you experience here on Earth. To experience that kind of pressure, you would need to swim down 1 km beneath the surface of the ocean. Venus’ atmosphere is made almost entirely of carbon dioxide, and not the oxygen/nitrogen mix we have here on Earth.

          The clouds we see on Venus are made up of sulfur dioxide and drops of sulfuric acid. They reflect about 75% of the sunlight that falls on them, and are completely opaque. It’s these clouds that block our view to the surface of Venus. Beneath these clouds, only a fraction of sunlight reaches the surface. If you could stand on the surface of Venus, everything would look dimly lit, with a maximum visibility of about 3 km.

          The upper cloud deck of Venus is between 60-70 km altitudes. This is the part of Venus that we see in telescopes and visible light photographs of the planet. The clouds on Venus rain sulfuric acid. This rain never reaches the ground, however. The high temperatures evaporate the sulfuric acid drops, causing them to rise up again into the clouds again.

          Venus spacecraft have detected lightning on Venus, coming out of the clouds with a similar process to what we have on Earth. The first bursts of lightning were detected by the Soviet Venera probes and later confirmed by ESA’s Venus Express spacecraft.

          Early astronomers claimed that Venus was Earth’s sister planet. They believed that the light and dark areas they saw on the planet through their telescopes were oceans and continents. Modern astronomy has proved that nothing could be further from the truth! The light and dark areas are Venus’ suffocating atmosphere — a layer of clouds containing sulphuric acid released by volcanic eruptions. The temperature on Venus can rise to 464°C (867°F), and the heavy layers of cloud make the air pressure on the surface over 100 times that of Earth.

          Venus is the second planet from the Sun and our closest planetary neighbor. Similar in structure and size to Earth, Venus spins slowly in the opposite direction from most planets. Its thick atmosphere traps heat in a runaway greenhouse effect, making it the hottest planet in our solar system with surface temperatures hot enough to melt lead. Glimpses below the clouds reveal volcanoes and deformed mountains.

          Had Venus drawn slightly luckier tickets in the cosmic lottery, our solar system could host two habitable planets today, according to recent simulations from a group of NASA researchers. Instead, our neighbor is a desolate place—and might give us a terrifying glimpse of our own future.

          Planetary scientists have traditionally viewed Venus's hellish temperatures, carbon dioxide-saturated atmosphere, and congealed crust as the inevitable outcome of its place in the solar system. Sitting too close to the sun, the hapless planet was doomed from birth to be burnt to a crisp. In recent years, however, an alternative possibility has thrown some shade at this simple story. Given the right starting conditions, cloud cover could have protected Venus from the barrage of sunlight and kept it balmy and wet for billions of years, according to simulations presented this week at a planetary science conference in Switzerland. In this scenario, Venus may have actually been the solar system’s first habitable planet… until some unknown catastrophe smothered it in carbon dioxide. While our carbon emissions probably couldn’t completely fry the Earth in quite the same way, the transformation of Venus may still hold an important moral for humanity.

          “If there was life on Venus, they only had one home,” says Colin Goldblatt, a planetary scientist at the University of Victoria in Canada, “and that home isn't very good anymore.”

          Craters are the most widespread landforms in the solar system. Craters are found on all of the terrestrial planets—Mercury, Venus, Earth and Mars. The surfaces of asteroids and the rocky, ice covered moons of the outer gas planets are cratered as well. The craters left by impacting objects can reveal information about the age of a planet's surface and the nature and composition of the planet's surface at the time the crater was formed.

MERCURY AND THE MOON

          Impact craters dominate the surfaces of Mercury and the Earth's Moon. Both bodies lack liquid water on their surfaces that would erode impact craters over time. They also lack an atmosphere which, on planets like the Earth and Venus, could disintegrate meteoroids before they impact the surface. However, old craters can be eroded by new impact events. Mercury and the Moon have very old surfaces. One of the youngest large craters on the Moon is Tycho, which was formed about 109 million years ago.

EARTH

          Liquid water, wind and other erosional forces erase impact craters on the Earth. There are still many craters on Earth which are visible from space. Some craters in areas of low rainfall (i.e. where little erosion occurs) are relatively intact, such as this crater - Meteor Crater in Arizona, U.S.A.

MARS

          Mars has experienced significant bombardment. The southern hemisphere is more heavily cratered than the northern hemisphere. Winds are the main erosional force on Mars and windblown dust and soil erode craters over time. The structure of some Martian impact craters, such as the one pictured here at left, provide evidence that suggests the presence of water or ice in the surface at the time the impact occurred.

ASTEROIDS

          Asteroids are rocky and usually heavily cratered due to a long history of impacts with other asteroids and possibly comets. Old impact craters on asteroids have beem deformed and erased by newer impact craters. Alternatively, impact events can disintegrate asteroids into smaller pieces. This asteroid, Mathilde, is interesting because of the large size of the impact craters on its surface. Despite the obvious intensity of the impacts, the asteroid was not destroyed. Scientists believe the asteroid must be  uncommonly dense to have withstood such bombardment.

PLANETARY SATELLITES

          The outer gas planets do not have solid surfaces, but their moons do. Most of these moons are rocky, icy worlds with a variety of surface features and compositions. Most of them are cratered, such as Europa, one of the Galilean satellites of Jupiter. Europa's surface is thought to consist of a thick layer of ice overlaying a liquid water ocean.

IMPACT WITH JUPITER

          Terrestrial planets aren't the only ones that are hit by meteors, comets and asteroids. The planets known as gas giants, such as Jupiter, don't have a solid surface to keep a record of impacts. However, the impact of comet Shoemaker-Levy in 1993 left visible holes in the cloud tops of Jupiter. The effects of these holes began to fade after only a few months, but it was the first time humans observed a major collision between two objects in our solar system.

          Mercury is the innermost planet in the solar system. Since it is the closest to the Sun, Mercury is the most difficult planet to see because it is always seen quite near to the Sun in the sky and the Sun's glare or the bright sky usually overwhelms the planet's light.

          The only chance to see it is as a faint "star" in the morning or evening sky near the horizon, shortly before sunrise in the dawn or just after sunset in the dusk. So it has always been almost impossible to get any information about the surface of the planet by means of ground-based observations. The first, detailed images were obtained with the NASA Mariner 10 spacecraft which also procured most of our present information about Mercury's surface.

          Like our Moon, Mercury is small and its surface is scarred by craters that were formed by impacting rocks and asteroids, soon after the birth of the solar system. They smashed into the planet and blasted the material away from the surface. Mercury also has real cliffs, or scarps which formed when the young cooling planet shrunk like an old apple, with wrinkles on its surface.

          Mercury has the largest day-to-night temperature variation of all planets. The days are burning hot (about 400 °C) and the nights are freezing cold (about -200 °C). This is because it only has a very thin atmosphere.

         Mercury is one of the most heavily scarred objects in the Solar System. Thousands of meteor craters cover the planet, including the largest — the Calories Basin. This was formed when a piece of rock 100km (60 miles) wide collided with Mercury 3.6 billion years ago. Mercury is also shaped by wrinkles and cracks that formed when the surface of the planet cooled and shrank.

          The orbit of Mercury is the most eccentric of the planets in our Solar System. The planet has an orbital period of 87.969 Earth days. At perihelion it is 46,001,200 km from the Sun and at aphelion it is 69,816,900 km, a difference of 23,815,700 km giving it an eccentricity of 0.21. Mercury’s orbit is inclined by 7 degrees to Earth’s ecliptic. Mercury can only be seen crossing the face of the Sun when the planet is crossing the plane of the ecliptic and is between the sun and Earth. This happens about once every seven years.

Source: Orbit of Mercury – Universe Today

          A more precise value of the eccentricity of Mercury's orbit is 0.205 630. By comparison, the eccentricity of Earth's orbit is 0.0167086, and the eccentricity of the orbit of Venus is 0.006772.

          Mercury is locked in a 3:2 spin-orbit resonance making three rotations about its spin axis every two orbits about the sun. Because of this, if you were on the surface of Mercury, the Sun would pass overhead once every two orbits around the Sun, or 176 Earth days. In other words, one day on Mercury (sunrise to sunrise) takes two Mercury years. A Mercury year takes 88 Earth days, the length of time to orbit the Sun.

Source: Mercury’s Orbit

          So one solar day on Mercury is about 176 Earth days, and one "Mercury day" (a sidereal day or the period of rotation of Mercury around itself) is equal to approximately 58.7 Earth days.

         And there is also the precession of the perihelion of Mercury. The closest distance of Mercury from the Sun doesn't happen at the same place but moves slowly around the Sun. The other planets of the solar system have perihelion shifts, but classical mechanics did not give an accurate value of Mercury's perihelion precession. The General theory of Relativity was able to show and predict that Mercury's orbit shifts by about 43 seconds of arc per century.

          The planet Mercury is often cited as the most difficult of the five brightest naked-eye planets to see. Because it's the planet closest to the Sun, it never strays too far from the Sun's vicinity in our sky. It is often referred to as "the elusive planet." And there's even a rumor that Copernicus, never saw it, yet it's not really hard to see. You simply must know when and where to look, and find a clear horizon. And for those living in the Northern Hemisphere, a great "window of opportunity" for viewing Mercury in the evening sky is about to open up.

          Mercury is called an "inferior planet" because its orbit is nearer to the Sun than the Earth's. Therefore, it always appears from our vantage point to be in the same general direction as the Sun. In the pre-Christian era, this planet actually had two names, as it was not realized it could alternately appear on one side of the Sun and then the other.

          Mercury was called Mercury when in the evening sky, but was known as Apollo when it appeared in the morning. It is said that Pythagoras, about the fifth century B.C., pointed out that they were one and the same.

          Because of its proximity to the Sun, Mercury is a very difficult planet to explore. It is normally obscured by the Sun’s glare, which prevents even observatories such as the Hubble Space Telescope from peering at it because of the risk to light-sensitive equipment. Mariner 10 is the only probe to have visited Mercury, but it too could only photograph half the planet.