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What’s up? Night sky for April 2011

Amateur astronomers using a telescope at dusk

Autumn nights are ideal for stargazer. Autumn mornings too, with some planets making a welcome return to our pre-dawn skies.

LIKE LAST MONTH, Venus is the star of the show in April, high in the eastern sky before sunrise. You can’t miss it—it is big and bold and brilliant.

Mercury makes a reappearance in the eastern morning sky from mid-month. As the April progresses, you’ll notice it rising higher and higher in the sky.

Ditto for Mars, which has been lost from view in the glare of the Sun for a while, but is making a reappearance in the morning sky this month, very low down in the east.

The largest planet in the Solar System, Jupiter, will also be low down on the eastern horizon before sunrise during April.

So that’s four planets all quite near to one another in roughly the same part of the sky! Definitely worth getting up early for.

Shifting to the evening sky, and the ringed planet Saturn will be bright and bold in the eastern sky after sunset.

Except where indicated, all of the phenomena described here can be seen with just the unaided eye. And unless otherwise specified, dates and times shown here are for the Australian Eastern Standard Time zone, and sky directions are from the point of view of an observer in the Southern Hemisphere.

April 1

Have a look out to the east before sunrise and you’ll see the Moon just below the planet Venus. You can’t miss Venus—apart from the Moon and the Sun, it’s the brightest thing in the sky!

April 2

Today the Moon will be at the farthest point in its orbit, called apogee, at a distance from Earth of 406,657 kilometres.

Also, you’ll notice that compared to yesterday the Moon has moved downwards in the sky and away from Venus. Now, it will be closer to the planet Mars, which is fainter than Venus and a ruddy colour.

April 3

New Moon occurs today at 11:32pm Sydney time (April 3, 14:32 Universal Time).

April 4

The planet Saturn reaches opposition today. This is a fancy way of saying that, from an Earth-bound observer’s point of view, it is in the opposite side of the sky to the Sun. In other words, if you could look down on the Solar System from above, the Sun, Earth and Saturn would be in a line, with Earth in the middle. Opposition generally is a good time to view a planet.

Stargazers with telescopes

Take the opportunity to get out and do some stargazing before the weather becomes too cold

April 7

The planet Jupiter reaches conjunction with the Sun today, which is a fancy way of saying that it is on the other side of the Sun as seen from Earth…although, being on the other side of the Sun, we can’t actually see it. You can think of conjunction as being the opposite of opposition (see April 4 above), so to speak. If you could look down on the Solar System from above, you’d see Jupiter, the Sun and the Earth in a line, with the Sun in the middle.

April 10

Today, the innermost planet, Mercury, reaches ‘inferior conjunction’. This is another kind of conjunction, again signifying that certain celestial bodies are in a line. In this case it is the Sun, Mercury and the Earth in a line, with Mercury in the middle. This makes it impossible to see the tiny planet, as it is lost in the glare of the Sun.

On certain special occasions, the tilt of Mercury’s orbit means that it can be seen crossing the face of the Sun when it is at inferior conjunction, in an event known as a transit. That’s not the case here—the next one will be in 2016.

April 11

It is First Quarter Moon today at 9:05pm Sydney time (April 11, 12:05 Universal Time). First Quarter is a good time to look at the Moon through a telescope, as the sunlight angle means the craters and mountains are throwing nice shadows, making it easier to get that 3D effect.

April 14

The almost-full Moon will appear close to the star Regulus in this evening’s sky. Regulus is a large, blue star, and is the brightest star in the constellation Leo.

April 17

Today the Moon will be at the closest point in its orbit, called perigee, which is the opposite of apogee (see April 2). The distance between the two bodies today will be 358,090 kilometres.

Still on the Moon…take a look slightly below and to the left, and you’ll see a bright whitish-yellowish star. Well, that’s not a star, it’s the planet Saturn. If you have a telescope, or have a friend who has one, zero in on it and you’ll get a lovely view of its magnificent rings.

April 18

Full Moon occurs today at 11:44am Sydney time (April 18, 02:44 Universal Time). You won’t actually be able to see the Moon at that time, as it will be below the horizon. But take a look at sunset, and you’ll see that as the Sun sets in the west, the big, bright Moon will rise in the east.

April 20

Two planets get to say hello to each other this morning. In the eastern sky before sunrise, Mars and Mercury will appear close to each other. Be warned, though, that they will be very low down toward the horizon, so you’ll need a clear view if you’re to see them.

Over the next few weeks, four planets will be seen together in the morning sky. Here’s a short video from Tanya Hill, astronomer at the Melbourne Planetarium, explaining what we can expect to see:

April 21

Today will be an interesting to demonstrate to yourself how the Moon moves through the sky. If you get up in the morning while it’s still dark, take a look slightly above the Moon and you’ll see a ruddy-coloured star. That’s Antares, the brightest star in the constellation Scorpius. Remember that view. Now, go back outside later today in the mid-evening and find the Moon again, and you’ll see that the separation between the two has increased. This shows you how the Moon has trundled along a bit in its orbit throughout the day.

April 25

It is Last Quarter Moon today at 11:47pm Sydney time (14:47 Universal Time).

April 30

Today the Moon will again reach the farthest point in its orbit, apogee, at a distance from Earth of 406,038 kilometres. Take a look out to the east this morning and you’ll see the crescent Moon with Venus, Mercury, Mars and Jupiter (refer to the video above).

If you have any questions or comments on the night sky, we’d be happy to answer them. Please use the Feedback Form below. Happy stargazing!

Images courtesy IAU.

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What’s up? November’s night sky

Amateur telescopes pointed at the sky

November is a good month for stargazing. If you have a telescope or binoculars, great—but don't worry if you haven't, as all of the phenomena described below can be seen with the unaided eye.

The planets Venus and Saturn make a welcome re-appearance this month, out to the east in the morning sky. You won’t miss Venus—it’s the biggest and brightest light in sky (after the Sun and Moon, of course). Saturn will be to the north of Venus.

Mars is still in the western sky, low on the horizon after sunset and getting lower with each passing day. Mercury is doing the opposite—it is low on the western horizon after sunset but rising higher each night. It will appear close to Mars in the second half of the month.

The giant planet Jupiter is high and bright in the northern sky during November evenings. If you have a telescope and know exactly where to look, you’ll be able to spot the seventh planet, Uranus, nearby to Jupiter. Unfortunately, for most observers it is too dim to be seen with the naked eye.

The Leonid meteor shower will make its once-a-year appearance again this month, with the possibility of meteors being seen over about a one-week span in the middle of the month. The best date to try and see them will the 18th.

Except where indicated, all of the phenomena described here can be seen with just the unaided eye.

Dates and times shown here are for the Australian Eastern Daylight Time zone, and sky directions are from the point of view of an observer in the Southern Hemisphere.

Amateur telescopes pointed at the sky

An astronomy club is a great place to learn more about the night sky. Check out the list of clubs by clicking on the Links button at the top of the page.

November 4

The Moon will be at perigee today, which is the closest point in its orbit around the Earth. The distance between Earth and Moon will be 364,189 kilometres.

November 6

It’s New Moon today.

November 7

The thin crescent Moon will appear close to Mercury. You might have difficulty seeing them if there are buildings, trees, hills etc in the way. Assuming you do have a clear horizon, you might even need a pair of binoculars to spot them, as they’ll be very low on the western horizon.

November 8

Watch for the Moon next to Mars.

November 14

It’s First Quarter Moon today, which is halfway between New Moon and Full Moon. And take a look into the western sky after sunset, and low down near the horizon you’ll see Mars next to the red supergiant stars Antares in the constellation Scorpius. Compare the colour and brightness of Mars and Antares—Antares means “rival of Mars”.

November 15

The Moon will be at apogee today, which is the farthest point in its orbit around the Earth. The distance between Earth and Moon will be 404,634 kilometres.

November 16

Watch for the Moon near to the giant planet Jupiter tonight, high in the northern half of the sky.

November 17

There’ll be an interesting grouping low in the western sky tonight after sunset, with Mercury sitting between Mars and Antares.

Meteor in the night sky

A meteor flashes across the night sky. The Leonid meteor shower is predicted to reach its annual maximum in the early morning hours of November 18.

November 18

The early hours of this morning will probably be your best bet to see some of the Leonid meteor shower meteors. You’ll have to be an early riser, as the best time to see them will be after 4:00am. Look to the north-east, about halfway up from the horizon. From a very dark location, you might expect to see about 20 meteors per hour. If you live in a light-polluted town or city, you can expect to see fewer.

Leonid meteors are pieces of tiny dust and debris left in the trail of a comet called Tempel-Tuttle (after its two discoverers). Floating through space, they run into Earth’s atmosphere at a huge speed (around 70 kilometres per second!), so it’s no wonder they put on a light show as they disintegrate in the upper atmosphere.

November 19

Watch for Mars and Mercury near to each other tonight, low down on the western horizon after sunset.

November 21

It’s Full Moon today. Have a look and see if you can see a faint star cluster near to the Moon. This is the Pleiades, or Seven Sisters, a pretty grouping of stars in the constellation Taurus.

November 29

It’s Last Quarter Moon today, which is halfway between Full Moon and New Moon. Take a look at the Moon, and nearby you’ll see a fairly bright, bluish-coloured star. This is Regulus, the brightest star in the constellation Leo.

If you have any questions or comments on the night sky, please use the feedback form below. Happy stargazing!

Images courtesy IAU.

Get SpaceInfo.com.au daily updates by RSS or email! Click the RSS Feed link at the top right-hand corner of this page, and then save the RSS Feed page to your bookmarks. Or, enter your email address (privacy assured) and we’ll send you daily updates. Or follow us on Twitter, @spaceinfo_oz