Galaxy helps astronomers measure the size of the universe

Trying to measure the size of the universe is no easy task. We know that the universe is expanding, though the exact rate of this expansion is not yet fixed. So one method that astronomers use to tell how far away very distant objects are is called the cosmic distance ladder.

The idea is that different objects can be used as rungs on a ladder for measuring different distances, from looking at the movements of stars to observing pulsating stars called cepheid variables to observing a type of supernova called a Type Ia. Each of these classes of objects is useful for determining increasingly large distances, but they need to be calibrated to each other to be accurate. Cepheid variables change in brightness over time, and importantly, the speed of the changes in brightness is correlated to their true brightness (as opposed to how bright they appear in the sky). So when we see a star pulsing we can work out its true brightness, and by comparing this to its apparent brightness, we can work out how far away it is.

The NASA/ESA Hubble Space Telescope's Wide Field Camera 3 imaged this lonely spiral galaxy called UGC 9391. /p pThe galaxy resides 130 million light-years from Earth in the constellation Draco near the north celestial pole. Its star-studded spiral arms stand in splendid isolation against a backdrop of distant galaxies, which are only visible as indistinct swirls or smudges thanks to their vast distances from Earth. The NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 imaged this lonely spiral galaxy called UGC 9391. ESA/Hubble & NASA, A. Riess et al

For even more distant objects, we can use Type Ia supernovae as yardsticks, because these explosions always have approximately the same level of brightness — so once again, we can compare the apparent brightness to the true brightness to work out how far away they are.

But, to measure distance accurately, we need a way to check that distances calculated based on cepheids are calibrated to distances based on supernovae. That’s where galaxies like UGC 9391 come in, which both contains cepheid variable stars and recently hosted a Type Ia supernova. This week’s image from the Hubble Space Telescope shows this handy distance-measuring tool in all its glory.

“UGC 9391 helped astronomers improve their distance estimates by providing a natural laboratory in which to compare two measuring techniques – supernova explosions and Cepheid variables,” Hubble scientists explained. “Improving the precision of distance measurements helps astronomers quantify how quickly the universe is expanding – one of Hubble’s key science goals.”

Editors’ Recommendations

Tags:

hawes-and-curtis listed on couponmatrix.ukkeytours listed on couponmatrix.ukpet-plan listed on couponmatrix.ukphase-eight listed on couponmatrix.ukpriority-pass listed on couponmatrix.ukthe-leisure-group listed on couponmatrix.uk
hawes-and-curtis listed on couponmatrix.ukSince its inception, the Hawes and Curtis heritage brand has been adored by the British aristocracy and Hollywood elite. With notable customers including the Duke of Windsor, Cary Grant and Frank Sinatra, you’ll be keeping good company while shopping affordably for menswear with a Hawes and Curtis discount code. Bringing true British style and class to everyone, Hawes and Curtis also offer a generous women's wear section too.
keytours listed on couponmatrix.ukLovers of classical culture, sun, sand and Mediterranean meze can let the good times roll, with a helping hand from Keytours discount codes. The tour guide company specialises in aiding visitors to Greece in experiencing Greek culture and exploring the country’s rich past and present. Groupon wants to pitch in, helping you to get away with Keytours promo codes. Keytours has a comprehensive range of tours across Greece to satisfy travellers of every variety, from history buffs to those after a relaxing retreat. One thing all customers have in common is that they can save money with Keytours promo codes, whatever the reason they are visiting. History is probably Greece’s biggest asset, with hundreds of famous ruins from the ancient world, such as the glorious Acropolis in Athens, that can be seen on Keytours’ excursions. Ruins, museums and places of historical interest aren't limited to the capital – they can be found across the entire country, including on its numerous islands. As well as cultural tours, the company also offer the chance to engage in activities. Customers can go scuba diving, sea kayaking, explore beaches and take geological tours of islands such as Milos, Rhodes and Kos. Fancy a spot of sun, sand and sea? Why not use Keytours voucher codes and discover a culture and country filled with thousands of years of civilisation. Whether you fancy Athens, Corinth, Mykonos or Kos, Groupon can help you explore Greece with Keytours discount codes.
pet-plan listed on couponmatrix.ukKeep your furry friends happy and protected with Petplan, the pet insurer that’s kept animals safe and their owners' finances secure for over four decades by ensuring 98% of their lifetime policy claims are paid. Whatever policy you choose from the UK's number 1 pet insurer, put the price of your plan down to size with a Petplan discount code and join the family of over 1.3 million protected pets for less. With no added fees for claiming and dozens of awards under their belt, it's of little surprise that Petplan remains one of the most trusted pet insurers - with over 90% of their customers renewing their policies each year.
phase-eight listed on couponmatrix.ukPhase Eight started in 1979 as a small boutique in Wandsworth Common London by young mother Patsy Seddon, who was committed to selling fashion that was both sophisticated and affordable. Today they stay true to their founding principle by offering an original design-led fashion brand for customers looking for beautiful and affordable clothing. With the help of one of a Phase Eight discount code, you could save a tonne of money on exclusive designs, luxurious fabrics textures and finishes that are flattering for all women.
priority-pass listed on couponmatrix.ukGet your journey off on the right foot with an airport lounge experience from Priority Pass. Access the world’s largest independently owned lounge program and slip into the holiday mindset with complimentary drinks, snacks and a tranquil, soothing space. Don’t forget to snap up a Priority Pass discount code from us when you sign up to join, and you could relax and enjoy a little bit of luxury before every flight without breaking the bank.
the-leisure-group listed on couponmatrix.ukHave a great day out for all the family with MFA Bowl, the bowling, golfing, party destination! Located in spots throughout the UK, head to your local MFA for a great day of classic 10 pin bowling, test your stuff against friends, get the kids out for a fun time, or spark romance on a first date. Get tickets with an MFA Bowl voucher and you’ll be heading off for fun without it breaking the bank. Book a Birthday, grab some food, hit the lanes and have a great time, all from MFA Bowl.