Viete, že Sírius je hviezda, ktorá bliká a hýri farbami?

Napísal Počasie & Radar 11. január 2024

Určite ste si pri pohľade na nočnú oblohu všimli, že niektoré hviezdy občas bliknú, zažmurkajú a farebne sa rozžiaria. Najznámejšou hviezdou, ktorá takto mení farbu, je Sírius. Čo presne spôsobuje tento optický jav? Ako túto hviezdu môžeme pozorovať? Bude to možné aj dnes?

"Psie dni" alebo história Síria

Sírius vždy priťahoval pozornosť ľudí svojím jasom. Podľa Síria sa kedysi riadili staroveké kalendáre.  Hviezdu Sírius poznali už v starovekom Babylone, Egypte a Mezopotámii. V starovekom Grécku a Ríme existovali aj tzv. psie dni (dies caniculares). Tie ohlasovali najsuchšie a najteplejšie obdobie roka. Riadili sa okamihom, keď bolo možné tesne pred východom Slnka pozorovať hviezdu Sírius. V Stredozemnom mori k tomu dochádza medzi 22. júlom a 23. augustom.

Ako vzniká farebné blikanie?

Farebné blikanie a zdanlivé chvenie hviezd sa pripisuje optickému javu nazývanému scintilácia. Najvýraznejšie sa prejavuje pri hviezdach nízko nad obzorom, napríklad pri dvojhviezde Sírius v súhvezdí Veľkého psa. Keď sa hviezda pohybuje vyššie nad obzorom, blikanie slabne a mení sa na rovnomernú žiaru.

Scintilácia vzniká pri prechode svetla hviezd cez turbulentné vrstvy zemskej atmosféry, ktoré sa líšia teplotou a hustotou. V tomto prípade plynný obal Zeme funguje ako obrovská sústava šošoviek. Stúpajúce bubliny teplého vzduchu rozdeľujú lúče z hviezdy na rôzne farby spektra. Vďaka tomu hviezda bliká, žiari a pri pohľade cez ďalekohľad skáče. Pri hviezdach vysoko nad obzorom nie je tento efekt taký výrazný, pretože svetelné lúče prechádzajú cez tenšiu vrstvu vzduchu.

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Sírius Zdroj: Počasie & Radar

Prečo planéty žiaria trvalo?

Planéty na rozdiel od hviezd nesvietia vlastným svetlom, iba ho odrážajú, takže scintilácia je v prípade týchto objektov zanedbateľná. To sa dá použiť aj ako jednoduchá pomôcka pri rozlišovaní, či je objekt planéta alebo hviezda.

 

 

Kde presne môžeme nájsť Sírius a ako pozorovať scintiláciu?

Sírius je najvýraznejšia hviezda zo všetkých a je prvou hviezdou, ktorú v zime po západe Slnka vidíme. Nemala by sa zamieňať s jasne žiariacou Venušou či Jupiterom. V prípade Síria je farebné blikanie veľmi nápadné a pozorovateľné voľným okom. Je to jasná dvojhviezda, ktorá sa nachádza v súhvezdí Veľkého psa neďaleko Orióna. Vidieť ju možno približne od 19.00 hod. na juhovýchodnom obzore. Potom sa presúva cez juh a zapadá okolo 4. hodiny na juhozápade.

 

Zaujímavý zážitok nám umožní pohľad cez ďalekohľad alebo fotoaparát so zoomom. Pre tých, ktorí vlastnia zrkadlovky, sa odporúča objektív s ohniskovou vzdialenosťou aspoň 200 mm. Ďalšou možnosťou je sériové snímanie s rýchlosťou niekoľkých snímok za sekundu. V tomto prípade odporúčame nastaviť vyššiu hodnotu ISO 3200 alebo vyššiu, aby sa kompenzoval krátky čas snímania.

Ako správne zaostriť alebo rozostriť?

Namierte prístroj na Sírius a mierne rozostrite, dokiaľ sa vám hviezda nebude javiť ako pravidelný kruh. Počítajte s tým, že pri priblížení vám hviezda "ujde zo záberu". Je to spôsobené rotáciou Zeme, ktorá začne mať výrazný vplyv na kvalitu a schopnosť efektívneho snímania pri väčších priblíženiach. Potom sa nám naskytne zaujímavé predstavenie pulzujúcej zmesi farieb. Vesmírna diskotéka sa môže začať!

Tip na záver: Ak natiahnete ruku a prižmúrite pri pohľade na prst, aby ste videli Sírius dvakrát, uvidíte, že v skutočnosti ide o dve nezávislé hviezdy. V každom oku bude blikať inou farbou.

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Ak pred nami je jasná noc, budú ideálne podmienky na pozorovanie Síria. Kliknite na meteoradar v aplikácii Počasie & Radar a dozviete sa aj to, aké budú dnešné nočné teploty.

31 komentárov

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    No, the dumbbell bench press is not dangerous if the athlete uses the correct form and lifts
    an applicable amount of weight. One of the first advantages of the dumbbell bench press is the
    greater range of movement. To maximize this benefit, the burden must be under your
    chest on the backside of the press. At the top of the press, you
    should bring the dumbbells together.
    Simply like some other weighted train, you have to be careful about its kind and method.
    Strengthen supporting muscles like the triceps and shoulders with workouts like dips, overhead presses, and skull crushers.
    Skipping a correct warm-up can lead to poor performance and increased harm threat.
    Dumbbells are harder to bench usually since
    you have too stabilize two different weights independently and
    with a barbell you're utilizing your two pectoral muscle tissue to push one stabilized weight.
    Following the method above should make your dumbbell bench press set up
    much smoother and eliminate these annoying little neck
    and shoulder tweaks.
    A respectable dumbbell bench press for the common male beginner is round 45%
    of body weight for a single repetition and both dumbbells mixed.
    Intermediates and superior lifters ought to be in a position to
    lift round 90% and 130% (respectively) for 1 rep. As good because the dumbbell bench press is,
    should you do it over and over again, your muscular tissues will soon adapt, and it'll cease being such a productive
    exercise.
    The mixture of shoulder joint horizontal flexion, shoulder girdle abduction, and elbow extension is very important in all forward reaching, grabbing, and
    pushing actions. The dumbbell press can be important in baseball and softball batting
    and in facet arm throwing. The flat bench press permits you to raise heavy weights, selling power gains in the chest, shoulders,
    and triceps. Common follow improves general urgent power, which interprets to better efficiency in different workout routines and daily actions.
    The incline bench press primarily targets the upper chest,
    extra particularly the clavicular head of the pectoralis main,
    anterior deltoid, and triceps. Additionally, the incline bench press recruits the forearms, lats,
    traps, rhomboids, and rotator cuff muscular tissues.

    Also generally recognized as flat DB bench press or dumbbell chest press, this train works on your general
    pectoral development. If you are looking to increase higher physique power, compete in strength
    sports activities, particularly powerlifting, and enhance the overall dimension of your chest,
    you should contemplate doing the flat bench press. The incline dumbbell press is a
    free weight train designed to focus on the chest, shoulders, and
    triceps, independently hitting all sides of the body. This
    train is a good way to give attention to and outline your upper-chest muscles.

    This train increases rigidity in your pecs, especially within the inner region. Additionally,
    because you must push the weights along with all your power, you
    won’t need to use as a lot weight as you'll for regular dumbbell
    bench presses. We actually don’t want to enter an excessive quantity of detail with
    dumbbell bench press variations as much of the targeted muscle tissue are the identical.

    Use the steps above for a standard bench press, however
    grip barbell with arms shoulder-width throughout the motion. Read
    on to be taught extra about bench presses and how to get probably the most out of this exercise.
    For constructing muscle mass, goal for 3-4 units of 8-12 repetitions for every
    train.
    Since your lower back is of course curved, it’s actually best to have a slight arch in your back.
    However definitely don’t exaggerate the arch like powerlifters typically
    do in competitors. After unracking the barbell, place your
    arms so they're completely vertical. Keep Away From these widespread errors to maintain your
    bench press safe and effective.
    Varying your routine with completely different weights,
    reps, and incorporating both urgent methods can help in preventing
    plateaus and constantly challenging your muscle tissue.
    Focus on the target muscles throughout presses to optimize
    engagement. Visualization techniques during dumbbell and bar presses might amplify muscle recruitment
    and development. A keen focus yields important enhancements in form and efficacy.
    These are must-have items of kit for trainers and customers who wish to have more
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    spotters by offering all the support needed to initiate train.
    Bear In Mind, it is extra important to have
    correct kind than large amounts of weight. As Quickly As you have mastered the technique, you'll add extra weight to your dumbbell bench press.
    By specializing in approach, you'll find a way to take advantage of the flat dumbbell press whereas
    lowering the risk of harm. Hold the dumbbells with a impartial grip,
    palms going through each other.three.
    Being sturdy within the bench press will allow you to achieve success in all other
    practical push actions, not to point out in sports and
    in life. The reason dumbbells are so great is that they provide a higher
    vary of motion they usually permit your arms
    to work independently, which may iron out muscle imbalances.
    Furthermore, it requires them to activate to a slightly larger diploma to stabilize.


    All three heads run into a common tendon which attaches to
    the olecranon means of the ulna bone in the forearm.

    Truthfully, the decline is the least important of flat, incline and decline bench presses for the typical
    lifter. You can get simply as good impact for the lower chest with weighted dips and its safer.
    Really flat and incline are an important bench press variations.

    Right Here are some answers from forums we've gathered that will help you
    predict what you probably can raise from those who have carried out
    so within the health club and at house. We gathered these from bodybuilding.com and different fitness websites and
    blogs from precise users. Place the weights on the finish of the bench to find a
    way to raise them from a position that is virtually straddling the bench…ready to sit down. Decreasing the weights quickly and "bouncing"
    them up off the top of your chest is ineffective. If you finish
    up doing this (or in case you are tempted to do so), that's a good indication that you're lifting extra weight than you should
    be. But with the proper train selection and workout routine,
    the task turns into a lot simpler.
    Whether Or Not your goal is to build muscle, increase power, or improve general
    upper-body performance, the flat dumbbell press is an invaluable
    addition to your coaching regimen. By progressively rising the load, the flat bench press stimulates hypertrophy,
    resulting in muscle progress. It’s a key train for anyone aiming to construct
    a a lot bigger and stronger chest. Sure you want to mix in both dumbbell press and barbell bench press.
    This will assist improve your power general and be in a position to
    break by way of plateaus when needed. Now if you solely have dumbbells it's fine to stick with them till you reach a
    plateau then switch it up and work in these barbell presses.

    They get shoulder pain from flat benching but appear to tolerate incline benching properly.
    Probably due to a extra environment friendly pressing
    angle by which extra of your chest muscle fibers
    can help. One Other issue may be the slightly shorter vary of movement of the flat bench
    press. The dumbbell press presents a greater range of movement than the barbell bench press.

    This makes it nice for each newbies and skilled lifters.
    Muscle growth is the goal of bodybuilders, but everyone can profit
    from muscle mass, which declines with age.
    As a general rule of thumb, if you would like more delt involvement press on the next incline, and for more pec, press from a decrease incline.
    Nonetheless, your front deltoids are active in pretty much any pressing exercise accomplished
    in front of your physique, and the degree of incline doesn’t appear to do quite so much of distinction. The term
    "press" can refer to any sort of exercise that uses a urgent motion to extend power and construct muscle.
    This can include workouts like the leg press, chest press, floor press, or overhead press.

    Bench presses work several completely different muscular tissues in your upper
    physique, together with the chest, shoulders, and arms.

    The bench press is a practical exercise that helps you
    extra easily perform day by day activities that
    require pushing or carrying. Whereas each goal the higher body, each
    exercise affects specific muscle tissue differently.
    For occasion, a small 2020 study showed that the overhead press prompts the
    deltoids more, whereas the bench press focuses extra on the chest.


    During this step, you may be making ready your body
    to execute the raise. This step is the inspiration of performing the dumbbell
    bench press. The triceps brachii is situated on the backside of
    your upper arm. When you straighten your arms, the dumbbell
    bench press works your triceps at the end of the press.
    Variations of the dumbbell bench press include the incline, decline, ground,
    wrist rotation, impartial grip, alternating, and single-arm.


    Starting with the Dumbbell Press, concentrate on a full range of motion. The incline press can be problematic
    for people who experience shoulder ache. If you've ongoing shoulder ache, attempt the exercise on a machine or with a barbell earlier than attempting it with dumbbells.


    The incline bench press is arguably the hardest of these
    three variations and that’s because of the vary of motion you’ll be working by way
    of. The incline bench has a larger vary of motion you’ll need to press via and you’ll need a great
    degree of mobility to carry out these. For newbies,
    I sometimes advocate tackling the flat bench press first
    and constructing a good foundation with this press.
    The flat bench press is probably the most "generalist" of these three bench variations
    and you’ll train a majority of the pecs with the flat bench.
    A standard flat bench can be utilized in place of a bench press rack,
    and you may perform bench presses with dumbbells or a barbell.

    If you wish to add bench presses to your weightlifting routine, try to
    carry out bench presses solely 2 to 3 occasions per week.
    Give your self a minimum of 1 day between doing bench presses to allow your muscular tissues to get well.

    Dumbbell bench press challenges are numerous targets or
    checks that an athlete can full. They are a method for athletes to push themselves
    to accomplish extra in the weight room. If you might be
    able to dominate the dumbbell bench press, you must comply with these six
    steps. Your elbows should be instantly under your wrists as you prepare to lower the dumbbells.
    Maintaining your elbows and wrists in alignment will hold your shoulders within the right place.
    To set your back, flex your shoulder blades and squeeze them
    collectively.

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