Category Astronomy

When did Voyager 1 and 2 enter interstellar space?

After Voyager 1 departed from Saturn in November 1980, it began its journey towards interstellar space. It crossed over to interstellar space on August 25, 2012, leaving behind the heliosphere – the enormous magnetic bubble encompassing the Sun, the planets and solar wind.

Voyager 2 headed towards interstellar space after departing from Neptune in August 1989. It entered interstellar space on November 5, 2018, six years after its twin did the same.

According to NASA, Voyager 1, the faster of the two probes, is currently over 13.6 billion miles (22 billion km) from the Sun, while Voyager 2 is 11.3 billion miles (18.2 billion km) from the Sun. It takes light about 16.5 hours to travel from Voyager 2 to Earth. By comparison, light travelling from the Sun takes about eight minutes to reach Earth.

Factfile:

The heliosphere is a bubble around the Sun created by the outward flow of the solar wind and the opposing inward flow of the interstellar wind, while the heliopause marks the end of the heliosphere and the beginning of interstellar space.

 

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Where do the spacecraft get their power from?

The spacecraft are powered by nuclear batteries (radioisotope thermoelectric generators) with electricity generated from heat produced by the decay of plutonium. While it is a pretty durable power source, it is not designed to last forever. The spacecraft loses power by roughly 4 watts every year. With power dwindling, some non-essential instruments on the spacecraft had to be shut off over the years to keep the mission going. For instance, in 2019, the primary heater for the cosmic ray subsystem instrument was turned off to reduce power consumption.

Each probe holds 11 instruments to carry out various tasks such as examining atmospheric chemistry, magnetic fields, charged particles, physical properties of the planets, and solar wind.

 

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When were the Voyager 1 and Voyager 2 launched?

Voyager 2 was launched on August 20, 1977. Its trajectory was designed to allow flybys of Jupiter, Saturn, Uranus, and Neptune.

Voyager 1 was launched first on a longer trajectory as it had to study the two outermost planets-Uranus and Neptune-in addition to Jupiter and Saturn. Voyager 1 was launched second in such a way that it could overtake Voyager 2, before reaching Jupiter.

 

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What are Voyager 1 and Voyager 2 programs?

In 1977, the U.S. space agency, NASA, launched an ambitious space programme-the Voyager-to study the four outer planets of the Solar System, namely Jupiter, Saturn, Uranus and Neptune. The mission employed two robotic probes, Voyager 1 and Voyager 2, on different trajectories. While the former was tasked to make a close flyby of Jupiter and Saturn, the latter was set to pass these planets on a wider trajectory, and explore Uranus and Neptune in addition. These spacecraft were initially designed to last only five years, but they outlived their expectations and their mission was subsequently extended. They continued their mission was subsequently extended. They continued their cosmic journey beyond the solar system into interstellar space.

It’s been 42 years since launch and both Voyager 1 and 2 are going strong and sending back data from more than 11 billion miles from the Sun. The track record is indeed outstanding, but the Voyager Program cannot go on forever. In 2019, NASA announced that both spacecraft will likely be retired by mid-2020s, as their power has been gradually dropping.

As if it was a sign of things to come, Voyager2 experienced a power glitch last month, which forced the spacecraft to go offline. But the NASA team fixed the problem and the probe’s science instruments resumed work.

In this week’s Five Ws & One H, let’s take a closer look at the Voyager Program and its monumental contributions to the field of astronomy.

 

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Which meteor showers most likely to be visible in the sky in 2020?

The Quadrantids

The Quadrantids give off their own New Year’s fireworks show. Compared with most other meteor showers, they are unusual because they are thought to have originated from an asteroid. They tend to be fainter with fewer streaks in the sky than others on this list.

Visibility: Between the end of December and the second week of January

The Lyrids

There are records from ancient Chinese astronomers spotting these bursts of light more than 2,700 years ago. They blaze through the sky at about 107,000 mph and explode about 55 miles up in the planet’s atmosphere. This shower comes from Comet Thatcher, which journeys around the sun about every 415 years. Its last trip was in 1861 and its next rendezvous near the sun will be in 2276.

Visibility: Between April 16 and 26

The Eta Aquariids

The Eta Aquariids are one of two meteor showers from Halley’s comet. Its sister shower, the Orionids, will peak in October. Specks from the Eta Aquariids streak through the sky at about 148,000 mph, making it one of the fastest meteor showers. Its display is better seen from the Southern Hemisphere where people normally enjoy between 20 and 30 meteors per hour during its peak. The Northern Hemisphere tends to see about half as many.

Visibility: Between April 19 and May 28

The Southern Delta Aquariids

They come from Comet 96P Machholz which passes by the sun every five years. Its meteors, which number between 10 and 20 per hour, are most visible predawn, between 2 a.m. and 3 a.m. It tends to be more visible from the Southern Hemisphere.

Visibility: From July 12 to August 23

The Perseids

The Perseids light up the night sky when Earth runs into pieces of cosmic debris left behind by Comet Swift-Tuttle. The dirty snowball is 17 miles wide and takes about 133 years to orbit the sun. Its last go-round was in 1992.

Usually between 160 and 200 meteors dazzle in Earth’s atmosphere every hour during the display’s peak. They zoom through the atmosphere at around 133,000mph and burst about 60 miles overhead.

Visibility: From mid-July to mid-August,

The Orionids

The Orionids are an encore to the Eta Aquariid meteor shower, which peaks in May. Both come from cosmic material spewed from cosmic material spewed from Halley’s comet. Since the celestial celebrity orbits past Earth once every 76 years, the showers this weekend are your chance to view the comet’s leftovers until the real deal next passes by in 2061.

Visibility: From October 2 to November 7

The Leonids

The Leonids are one of the most dazzling meteor showers and every few decades it produces a meteor storm where more than 1,000 meteor can be seen an hour. Cross your fingers for some good luck – the last time the Leonids were that strong was in 2002. Its parent comet is called Comet-Temple/Tuttle and it orbits the sun every 33 years.

Visibility: During mid-November

The Geminids

The Geminids, along with the Quadrantids that peaked in January, are thought to originate not from comets, but from asteroid-like space rocks. The Geminids are thought to have been produced by an object called 3200 Phaethon. If you manage to see them, this meteor shower can brighten the night sky with between 120 and 160 meteors per hour.

Visibility: First two weeks of December

The Ursids

The Ursids tend to illuminate the night sky around the winter solstice in the Northern Hemisphere. They only shoot around 10 to 20 meteors per hour. They appear to radiate from Ursa Minor, and come from Comet 8P/ Tuttle.

Visibility: Between December 17 and 26

 

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What is Meteor Shower and how to watch it?

If you spot a meteor shower, what you’re really seeing is the leftovers of the icy comets crashing into Earth’s atmosphere. Comets are sort of like dirty snowballs: As they travel through the solar system, they leave behind a dusty trail of rocks and ice that lingers in space long after they leave. When Earth passes through these cascades of comet waste, the bits of debris – which can be as small as grains of sand – pierce the sky at such speeds that they burst, creating a celestial fireworks display.

A general rule of thumb with meteor showers: You are never watching the Earth cross into remnants from a comet’s most recent orbit. Instead, the burning bits come from the previous passes. For example, during the Perseid meteor shower you are seeing meteors ejected from when its parent comet, Comet Swift-Tuttle, visited in 1862 or earlier, not from its most recent pass in 1992.

That’s because it takes time for debris from a comet’s orbit to drift into a position where it intersects with Earth’s orbit, according to Bill Cooke, an astronomer with NASA’s Meteoroid Environment Office.

The name attached to a meteor shower is usually tied to the constellation in the sky from which they seem to originate, known as their radiant. For instance, the Orionid meteor shower can be found in the sky when stargazers have a good view of the Orion constellation.

How to watch?

The best way to see a meteor shower is to get to a location that has a clear view of the entire night sky. Ideally, that would be somewhere with dark skies, away from city lights and traffic. To maximize your chances of catching the show, look for a spot that offers a wide, unobstructed view.

Bits and pieces of meteor showers are visible for a certain period of time, but they really peak visibly from dusk to dawn on a given few days. Those days are when Earth’s orbit crosses through the thickest part of the cosmic stream. Meteor showers can vary in their peak times, with some reaching their maximums for only a few hours and others for several nights. The showers tend to be most visible after midnight and before dawn.

It is best to use your naked eye to spot a meteor shower. Binoculars or telescopes tend to limit your field of view. You might need to spend about half an hour in the dark to let your eyes get used to the reduced light. Stargazers should be warned that moonlight and the weather can obscure the shows. But if that happens, there are usually meteor livestream like the ones hosted by NASA and by Slooh.

 

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